Actually, I agree that Robot Smoke got nerfed too much. They should have only nerfed one aspect of the character, and that would have balanced him and brought him down to where he needed to be. Nerfing his airthrow, damage, spear, and his invisibility seems a bit excessive. I think the nerf to this invis is fine to an extent, but the nerf along with the others he received brings him down too much.
In Vanilla UMK3, you don't really care when R.Smoke goes invis, at least, you don't have to worry too much because of GJs. The problem is that if you don't have the life lead, you can't just stand there and GJ because you would lose, you'd have to attack. This is one of the reasons I believe the invis is too good, it has no time limit, you can set it up to get it for free, and you can block during it. The problem is, ALL THREE of those aspects were nerfed, instead of just one or two. Now, it has a time limit, you can't get it off of a spear, and you also can't block when it is active. With H.Smoke, you can still get the invis during a combo, so his is a lot better.
I would suggest one of these three:
1. Make the invis limited, but allow blocking while it's active.
2. Make the invis limited, disallow blocking, but enable getting the invis off of a spear.
3. Make the invis UNLIMITED, but disallow blocking or getting it off of a spear.
At the very least, #2 needs to happen. I for one would vote for #1 or #3 though.