I think I can provide some insight on this, having recently pushed to endgame (SR 80 within time limit) on some not-so-straightforward characters. Expect a MASSIVE WALL OF TEXT, cause when I get into something, I go in-depth.
My perspectives of comparison here are experiences with:
- playing a straightforward “hit everything until it’s dead” playstyle with lifesteal
- relying on pseudo-pets and having to use “healing increased by %” mods to sustain via proc heals and Wendigo Totems
- playing a character with ZERO access to lifesteal from attacks (none of the attacks used had % WD on them or a lifesteal mod on an MI). The idea was to keep the character mobile, nuke quickly and with gusto from a distance and retreat, and take as many proc heals from the devo tree as possible to compensate.
- playing a summoner with next to no self-sustain, relying purely on not being attacked
- playing a pseudo-summoner built around regen
From these, lifesteal is the most comfortable way to regain health, by far. Almost every character outside of summoners or pseudo-summoners will be trying to stack a lot of on-character DPS. If you then pack some lifesteal on that (10+%) you essentially get to double dip. Every increase in DPS will now also increase your sustain, which you don’t get with any of the other methods of sustain.
As for “what if you have to run and can’t do damage to heal” that’s a problem you build around from the get go. You want to get your crowd control resistances up no matter what, so situations where you’re in the middle of everything and suddenly you can’t attack shouldn’t happen to you. And you want to build tanky enough to at least not get one-shotted, or rather, not get popped by a sequence of a strong debuff + several powerful hits. As long as you’re resilient enough to not get bursted down in a split second, lifesteal can get your health back to full at incredible speed, and you get to mostly ignore DOTs as long as there is something around for you to leech off of.
Building a character around any of the other methods of sustain, while possible, is definitely more niche. It’s harder to pull off, harder to pilot, more gear/devo/skill restrictive and more prone to things going wrong, because your level of sustain is essentially flat, regardless of how your DPS goes up or down based on short-term buffs. That means that if you’re sustaining just fine off of regen or Bat/Dryad when receiving normal levels of damage, if damage suddenly goes beyond normal and your regen can’t keep up, you’re gonna have a hard time fixing that problem in a meaningful way. Meanwhile, just getting 3% extra lifesteal on a lifesteal build can dramatically improve your survivability if you’re struggling, to the point where you don’t need to do anything else to fix the issue.
Example: my zero %WD, zero lifesteal character (Barrelsmith + Light’s Defender Purifier, using Quick Jacks, Grenado and Canister Bomb) could barely drag itself to SR75 (within timer) because there are situations where you just can’t avoid the damage. And since your massive burst damage yields you relatively minor, flat healing through stuff like Bat or Dryad instead of robust healing through lifesteal, what you end up with is a character that is scared of everything that hits any harder than average. If you run into enemies that just unavoidably charge at you or enemies that keep raining down destruction upon you from afar forcing you to kite more than do damage (Iron Maiden, Fabius, Moosilauke, Anasteria), and your meagre healing options aren’t keeping up, you’re done. Once the damage scales past a certain point, you simply can’t kill certain enemies. I was forced to abandon the idea for the character, drop Quick Jacks, drop the Light’s Defender set and include a minor auto-attack aspect in the build using the procs off of Barrelsmith. Suddenly, even with piddly little autoattack damage, the simple fact I had some lifesteal to sustain myself between Grenado and Canister Bomb casts allowed me to complete SR 80 deathless in two attempts. This method of sustain is still something that I intend to make work, since I have a handful of characters that simply do not have the option to go the lifesteal route no matter what (Trozan Druid, Blackwater spam Sorcerer), but I’d wager those characters will be extremely uncomfortable and will require major overhauls to their defenses in order to somehow withstand all the incoming damage.
The same goes for summoners. Iron Maiden and Fabius specifically will just periodically charge at your character if you stand back behind your minions, and especially in the case of Fabius, standing close to prevent him from charging you simply means taking incidental bursts of AoE damage the whole fight, until you run out of heals and die. If you don’t have other methods of healing beside your potion and you’ve gone past the difficulty threshold you can withstand (in my case it was SR82) you simply have to pray you can avoid those enemies. So the “don’t get hit” option doesn’t really work, unless you intend every major boss battle to be a tense 10 minute kitefest, where a single mistake gets you killed.
As for regen, the situation is a bit better, since you can get regen quite consistently to much higher levels than proc heals such as Bat or Dryad IF you dedicate your build to it. But it’s not just something you plop into your build through two or three support items. That’s a whole devotion path, mastery combo + gear setup to bring your sustain to comfortable levels. Sadly, my regen-based pseudo summoner is a multiplayer character, so I could get away with a more brazen build. My limited testing solo was somewhat promising, but I still couldn’t go off of pure regen (my peak with all procs active is only 6k health per second which is not enough) and had to supplement with Wendigo Totem…which forces me to stand still in situations where I can’t necessarily afford to.
TLDR: yeah, regen is doable. But I personally have one character where I’ve tried to pull that off, it isn’t quite there yet and I’m not sure where to get any more regen than what I have. Meanwhile, I have other characters that sustain off of lifesteal almost without trying, and others where trying anything else didn’t pan out, and going into even minor lifesteal suddenly turned the whole thing around.