I have no opposition to the perk changes not affecting pistol wielding Engineers. I think most people view the grenade engineers in terms of PvM/TS'rs so there should be a distinction between the applicable perk lines much as a melee or ranged advy would have.
I would however like to see Heavy Weapons added to the perk requirements along with Grenade. Given a Heavy Weapon choice, it would not be locked down to a specific weapon type as was stated as one of the goals. It would open up another possible weapon line for future development. They also use the same implant positions so they are effectively identical in drawbacks for achieving a higher AR, except for the grenade in the Syndicate symb.
My actual feeling is that all weapons that req Heavy Weapons should just require grenade instead and Heavy Weapons should be gotten rid of entirely. I don't see much use for Heavy Weapons given that it is in the exact same implant spots. I'd move Grenade over to ranged where it belongs, dump HW and move Sharp Objects to Melee, and get rid of the "Misc Weapons" button altogether.
But I digress.
Add Heavy Weapon to the Grenade line for the reasons stated above.
/brox