Its alright but the M16 is not really needed, you could try changing that for the FAMAS, ACR, or M4A1 Carbine.
UMPs again are very powerful(not really needed in hardcore), you could try changing that for a P90 or if you are good with it a Vector with a silencer.
Sniper is alright with the M21.
Thumpers are a good option in some times, I would just prefer using a grenade launcher as an attachment than the actual thumper(Sometimes you really need a secondary weapon)
The perk selection would be
Sniper:
-Sleight of hand(You don't really need marathon if you are sniping)/one man army(for those last man standing moments)
-Cold blooded
-Ninja
SMG:
-Marathon,
-lightweight/ Cold Blooded
-Ninja
Assault:
Marathon if you are rushing/Sleight of hand/ Bling if you need extra attachments
-Cold Blooded
-Ninja
*All pro upgrades are a better option for most of the perks.
Hope this helps you and your clan. I play more normal search and destroy than hardcore but I still do good in hardcore too, If you need some Normal S&

classes just ask for them.