I tag out just before the time hits, so I dont miss a respawn. I have had medics run by me and not revive so many times its not funny. I use the spawn host, but I dont think most folk know what to do with them.
As for the engineers I have to agree they can do a lot, unless there is a good sniper around. Every class has some benefits. A good field ops dropping art on their spawn will make a whole team come after you
I go 45 kills one game dropping arty on their spawn
and pissed off their whole team. Got three kick votes that game
Love it when you really piss them off