5 str is low for grenade launchers
10 dex is very high for a sniper/nade launcher build; I wouldnt do the throwing feats with these weapons
gunslinger doesnt fit
wait, does demo just mean grenades? so you're going pistols + sniper + throwing nades
in that case, id drop sure step for snipe, max stealth, drop split spare for blindsiding
id probably go with 7 dex, for gunslinger and three pointer; I wouldnt take bullet time
id go ahead and get escape artist too
psycho temporal acceleration and future orientation (+ spec points) would be good for this
if you took some psychokinesis as well, you could grab premeditation to use with electrokinesis or grounding
your chemistry is too high; you'd only want 112 max with all bonuses added in, and even then thats overkill imo, because plasma nades are generally better than mk5 regular nades
id drop merc completely, and at least one of your subterfuge skills, so you have enough for crafting and your psi skills
and obviously a teeny bit of evasion isnt doing you any good
but anyway, your build isnt terrible; it can work as is