Seriously. It just kind of... appears. And immediately gets stuck in a giant ball of CC and area effects.
Yeah, I always relax when I see him, ecause I know, nothing bad can happen from now on. Seriously that guy is a joke much like the KA ground boss... ^^
From the space bosses I like Donatra the most. She is interesting enough, but could defintly have a bit more punch on normal. The tactical cube next to the gate in infected is ok. But it is just a tac cube next to a gate which isn't really that special.
Oh, and the one time I could finish the cure ground boss off was with a PUG without medic. We died... alot!
Becky is reasonably puggable (Rebecca Simmons, Infected) on normal, Armek considerably less so. Whilst a medic can solo either of them, the sort of player that can pull it off isn't usually pugging normals, so that leaves a fair amount of luck needed, especially with Armek.
I'd have to say in pug groups, the infected console sequence or cure gates are frequently harder than the bosses on either difficulty.
As to the optionals, in Cure the only thing you need to worry about is the clock. Getting the gates down is usually the thing that blows the time but the optional is easily doable with time to spare. Personally, I think those are more of a pug barrier than Armek himself. Infected on the other hand, does need actually tactics and teamplay to get through the optional.