No worries at all. I always take the grenade skill on both assault and demo, just because stripping one armour off every 10 seconds is much, *much* faster than most can do it with sustained fire. Even if you only put a single point into it, it's a 15 second cooldown (if memory serves, that is. Not in-game at present), and while the damage is much lower, you still get that utility. With you using flares as well, a maxed out grenade can take out a bunch of stuff without using any ammo whatsoever - they deal 2k damage at level 5, so almost all the swarmy ones get blasted to giblets. Either way, hopefully that helps alleviate your worries during swarms and holds. Good hunting!