I always go with Assault Killstreaks on Support:
1) Sentry - Deploy a small turret
2) Straife Run - attack helicopter run
3) Pavelow - Large Armoured Helicopter
Works quiet well
As you said - I might go back to pure specalist.
I do like Extreme Conditioning / Assassin Pro /Steady Aim
with a Stealth Class Like: MP7 Silenced & MP9 Silenced