I like the spirit of these changes, but even with them gas will be relegated to an Infested-only damage type. Gas used to be a much more versatile type; weaker than other options against a single target of any faction, but strong against tight clusters of enemies of all factions. To that end, there are two other points I'd like to see addressed in some way:
Gas procs doing toxin damage was always over the top, but Gas damage itself is crippled by its modifiers against Flesh and Cloned Flesh; I'd like to see its existing bonuses and penalties dialed down on both ends.
As well as the triple-dip on banes--which deserved its nerf--Gas builds thrived on the way they previously scaled with your modded Toxin damage (which is still in line with the damage formulae for Heat, Electric, and Toxin procs); please restore this part of the calculation in some form.