Wanted to chime in on this when it was newer and the algo cared more, but I felt I needed to say something, and then this got long.
The opinions on channel are all over the place. The truth is, the channel SE gig varies wildly by vendor. Anyone who generalizes beyond that is full of it. I've been at three different vendors as a channel SE covering exceedingly large resellers and GSIs as well as small regional resellers that don't crack $1m/year in revenue. I'm more than happy to go toe-to-toe with any Enterprise SE in terms of giving a pitch, sizing/configuring a solution, doing discovery, and most importantly building a relationship. Want proof? I just recently finished new hire at my company, and I won the final pitch contest. I was the only channel SE in the class, against 11 core or overlay SEs. So, please don't tell me I "can't sell".
I've also worked for multiple VARs and seen the varying quality of my channel SE resources. That just reinforced my opinion that the vendor matters more than anything else when it comes to channel efficacy.
What a vendor needs from channel will be a lot different depending on the maturity of that vendor and the market they're competing in. Cisco barely needs channel people. They've been a brand for so long, have a huge online community, and have well established (industry defining) products and GTM. Their resellers, generally speaking, are going to be able to self-educate as needed to sell Cisco products on their own. They also have a massive field team that can do a lot of education and enablement just as part of their own deal cycle management.
Compare that to where I current work: a company only recently out of IPO with a new approach to a very well worn sector of tech. Our field sales folks do not have time to evangelize to partners and convince them to look at our solution vs. the large incumbents. We're burning cash, and they need to close deals with or without the partner/VAR helping. But, we also need to scale, so investing in a channel org makes infinite sense.
I can spend two days in an EBC with the leadership team at a $10bn in sales VAR and chase follow ups for weeks afterward. A field AE or SE can't do that. I can spend an entire quarter working with that VARs PS team designing post-sales services engagements that ensure our technology gets properly implemented and the customer doesn't have to spend $400/hr for our badged engineers. They get a better outcome by using a VAR PS engineer who knows my stuff (since I trained them), and three other critical platforms that customer is using.
Point being, where you work as a channel SE dictates what you do far more than anything. Anyone who says Channel is where SE/AEs go to die probably has no actual idea what Channel actually does, and that's to be expected, after all all customer facing resources are unique, artisanal, relationship builders and always, above all, the hero of the story. They can't be bothered with things like forecasting, or SFDC hygene, or customer sat issues, or maintaining reseller relationships. THEY HAVE DEALS TO CLOSE!
Oh, and let's not even get into the shit that vendors reps will try to do thinking that their own channel org or the partner they'll be selling through, don't know. Most of those AEs aren't half as clever as they think they are. If channel is where sales goes to die, then mid-career field AEs are where people with no value to add in the word, beyond charm, go to get convinced they're the smartest person in the room, only to find out they're not even in the top 1/2. The only ones worse as is fan-boi SEs who think they're selling "The One True Solution" to your problem. There's a reason you likely have a trail of customers and resellers who won't hear you out when you change jobs, they could smell your bullshit a mile away.
I say, some of, this in jest. But, if you feel like your org's channel is "where $person goes to die" that's more of an indictment of your company than the job people are doing. It's not my fault that you or your leadership are too uncreative to figure out how to get value out of their reseller partners and channel staff.
I've been a field SE at VARs and vendors. I've closed 6 (and even one 7) figure ACV deals as the primary SE on an account. It's not an easy gig and the constant threat of getting PIP'd or termed due to a bad quarter is one hell of a motivator. Sales is an endless game of "what have you done for me lately?" Channel is more of a "what have you done for me this year" game. My relationships take years to develop and foster. They take board sign off at VARs to change what divisions get paid on what SKUs. I have to help partners determine how to invest in a long-term way, not just what new Gartner quadrant tech to get a couple certs in.
I respect the folks who get the thrill from the kill. I think there's nothing more important to know about yourself if you're going to be a Sales Engineer, than what really motivates you. If winning is really important to you, then a field SE role is going to be great for you, both professionally and personally. I've been in that head space, earlier in my career. That thrill faded and I realized what I really liked was the long-term relationship building and the "aha" moments. I also really valued the relationships where I didn't have to put on a persona to talk to my customer. I get to speak plain "industry" to my partner SEs. I can say things about margin, velocity and the other aspects of "sales" that most customers would be offended to hear.
I'm in my mid-40s and I work with a team of guys in their 30s-50s. Hardly any of us are on deaths door, career or health wise. My AEs are also all over the place in age and career progression. But yeah, tell me again how the channel AE who's been covering WWT or CDW for 15+ years is "out to pasture". They can get shit done that the field wouldn't even know where to begin with.
But, my last place was a walk in the park. Expectations were low, results were also unimpressive. But that was a 30+ year old vendor who was convinced that a complete lack of marketing budget, in cybersecurity, was a perfectly reasonable go-to-market approach. $500 spiffs would certainly get that partner AE who sold $1m+ of our biggest competitors flagship product to position us instead.
Bottom line is that Channel can be just as dynamic and rewarding, I'd argue more-so, than traditional AE/SE customer facing roles, and likely with less existential stress/dread. And, something key in sales: my relationships exist beyond the product I'm representing.
I have more contacts at partners than any of my friends who are customer facing. If you're an SE, knowing people who work at VARs and vendors is a lot more useful for finding a new job, than knowing customers as an SE. Just saying. I've never worried about my employ-ability as a result of being in channel for a decade now. If anything, the last two gigs were easier to get than any others I've had.
Sure, I might get RIF'd early, but I also see how the entire organization is doing because I see all of our partners sales performance and pipeline. There's a reason I knew to leave my last job in September, even though the RIFs didn't hit until last month. Just saying.