I guess I disagree on a design level. I think every class should have the same capability of killing all the other infantry and the only really defining attributes for a class is utility. Ultimately it would be more restrictive.

Heavies would lose the overshield but gain grenade bandolier as a default and I'd look for another area to give them some utility. I'd make them the assault class, built for offense, and give them utility to do so. I'd make timed concs and detonate on impact concs 2 different types for different situations and let Heavies carry multiple grenade types. I like the idea of some type of explosive ammunition that doesn't benefit in 1v1s but is good against grouped enemies.

Medics would lose C4. Other than that I think they fit their role well.

Engineers would probably stay about the same. I think they tradeoffs they have to make for AV and AI are pretty good right now. If anything I'd push them to the more defensive class. Possibly give them access to RLs in the turret slot.

I'd give Light Assault access to recon darts and the dildar. Might look for something else to add if they don't have enough utility. Possibly make them a versatile class capable of taking 1 use only items that do things other classes already do, like a 1 limited use med tool or ammo box.

I don't know what I'd do with Infils but I think they are pretty much okay right now.

That isn't the game and it doesn't appear to be the design intent of the devs, so whatever. HAside it is I guess. I don't think a delay activation on Heavies is a good way to go about nerfs. a .9 permanent movespeed modifier seems fair, or making shield activation slow even more. I'd even consider not making Heavies benefit from .75 ADS at all.