I kinda like the idea, but why not nerf this insane suit a little more ?
3 armor points, with resistance to plasma/acid/fire, AND great movespeed boost looks like the best possible suit to me.
Sure, cerberi are fun, but they make you slow, and don't have those 3 flat protection points. Also, they don't regenerate, and O-modding them prevents from using an A or P instead.
The set bonus is really OP. Honestly, I didn't understand why the game's best armor has been buffed with this, while some other (really correct) armors could have been instead.
Why not put necro-boots, which give some ms and protection, and regenerate draining your health, but gib corpses you walk over for vampyre-like result when you get the set ? I'm sure most other unique armors could have fun pairs too.
Btw, (all) armors could also lose 25% efficiency when slightly damaged.
@Sereg : made my post more clear. No, plz, not 3 immunity sets, or then, make them useless for anything else... but this would suck. Just Neeeeeeeerf that damn malek !