I like the "slower pace" of TDM. I see plenty of rushers, some "campers," snipers, and all sorts of different playtypes. Between the AK74u and the FAMAS, if you want to rush, go ahead and rush. The weapons are there.
I don't really have sympathy for someone who isn't willing to stop for a second to throw a flashbang into a room. People want to say the CoD games have no strategy, but if the game slows down long enough for people to use tactics, then players complain it's boring. I'm much happier going 14-0 because I played wisely than 30-10.
As for Scavenger, the problem with it is that you really have to tailor your class around it. But if you do, it's powerful. I use it with concussions, semtex, AK74u, crossbows with Scav/Warlord/Tac Mask. You can pretty much spam concussions and figure out where the enemy is from Tac Mask. Scav replenishes them as fast as you can throw them, and this is really the key to the class. You rarely have to go into an encounter with an enemy that isn't stunned already. Near infinite semtex is nice too, even if you're just spacing your opponent. Then there's the AK74u with rapid fire and not having to worry about ammo. And crossbows + Warlord + Scav lets you have a strong secondary mini-grenade launcher. Each part of that class works with another piece, and it's my go-to class on Havana.