Everyone I've talked to who has used these weapons considers them poorly balanced garbage, except for one guy who thought it was decent and good enough. Last time I checked the Brits were considering replacing it with the G36 family. At least the polymer doesn't melt from bug spray in the A2 version... Not sure if the reciprocating charging handle will still break your teeth if you try to fire it from the left shoulder, though.
I guess it's nice to have in KF anyways, I've never seen the tanker carbine variant in any other game.