My general feeling regarding boss bots at the moment is that their health may be way too high all across the board, effectively leading to dealing with bosses being either impossible or samey (at least on higher difficulties).
As an example the TethysBots in my current game on Expert are level 10 with the 20000+ shields, 2000+ damage, 9 range and 50 ammo plus their special (which is interesting to deal with e.g. by deliberately hitting them with low damage weapons). But this all doesn't count much as effectively the only way to deal with them is virusing them: The damage output of my long range weapons is way too low to be able to kill one of these before it gets in range and even by stealthing away and trying again I would need 10+ shots to deal with one of these for instance - an unlikely amount of ammo if dealing with up to 7 of these.
Effectively the majority of usual and interesting ways to deal with bots (mines, turrets, long range fire, sneaking up on them for a high damage shot from behind cover, overload, ...) do not usually work for bosses in my games, making them really hard and fairly boring 
.
I also feel that the bots likely would not loose much of their threat potential even if halving their shields. These are still hard or at least costly to deal with if they occur combined with regular bots - at least in my book. I am curious as to what Misery will have to say about this. For me their stats are so superior that they effectively degenerate to one single boss type that I have to deal with the same way - always, which very much cuts the potential of how different bosses actually are or could be...
Hmm, I actually used pretty much every conceivable trick in the book when dealing with them.
I generally use a set of specific ideas when dealing with boss missions:
1. Dont enter one unless all Exos are in Epic form.
2. Dont enter one without having prepared very well for it; weapons full of equipment and as strong as possible, plenty of additional stealth, all that fun stuff.
3. Dont virus anything right away. Can very much lead to a loss here. Suddenly you wake up a bunch of things you dont want.... often including another boss. There are exceptions to this though.
4. DO use everything else. I remember that mission in the screenshot I posted. That mission was won by doing a few specific things: 1. Mines to soften up some of them, 2. turrets to do further ddamage from there. I always keep trap level for one of the Exos as high as it can possibly go, usually the sniper if I dont have a ninja. As such, chances are I can do ALOT of damage with these things. Turrets though arent just for doing damage; they can also hold a bot's attention, as the enemy bot will always take at least one turn to destroy a nearby turret, and often more turns than that to get into range to do so. A bot doing this is a bot that isnt shooting you. Particularly with the Vipers, this holds them in place long enough for me to deal some major damage to them. Heavy weapons are good during this point. When I've got something coming at me without having turrets around (did this with the Tethysbots), some high-powered shots as they approached, followed by reliance on the sniper's double-shot thing, and the Science Exo's chaingun. With the range on these set properly, these allow you to perpetually deal damage without allowing the enemy bot to ever get close, if you use them just right. I do this alot against really heavy bots. And since these are priority weapons, they're more buffed than most others, getting the strongest equipment. Combining these of course with even more turrets and mines when possible helps alot. Generally I go into these with ALOT of mines and turrets to spend. Ideally, I'll be dealing a few thousand damage to any given target per turn (usually including turns where I'm not directly firing at them), by using all of these different elements. And of course stealth helps with positioning, though if you're using alot of turns in a row for it, you're probably in a bad position.
The real thing that can be nasty is the open areas that these missions tend to take place in. It can make positioning.... interesting. Makes using the Brawler interesting too.
But yeah, that was typically my method of dealing with them, changed up a bit depending on which Exos I had on my team. Vipers being considered the most dangerous of the bosses, they would be dealt with the most carefully. The sniper-shot/chaingun technique simply doesnt work on them.
Now all of that being said, regardless of wether they're being properly difficult or not, if they're also being BORING, then yes, something could do with a change. Boring isnt fun, after all. And if you're not as effiecienty equipped, then yeah, even if you've got a very good situation with the level generator and positioning of everything, it can still be just plain time consuming to take those guys out.
Exactly what an overall shield drop will do to these guys in terms of difficulty, I'm not sure. Part of the challenge with them WAS the simple fact that they had so much shielding. You couldnt just quickly snipe them out of existence. You had to use more than just that, while dealing with whatever ability they had.
So that'll take some experimenting before I give much more feedback than that.
