if you just take your weed out of the kief compartment straight after grinding it, it wont lose any other than what it would have lost to the bottom of a grinder normally really.

HOWEVER, if you chose to shake or keep the weed in the compartment while moving it about or transportin it someone, the mesh will gently rub/grate trichomes off and will reduce the potency theoretically.

ya probably would find it hard to notice a differance/big differance unless you really shake the hell out of the weed for a few minutes wen in the tray with mesh.
I'd go for it, I got an acylic one (cheaper) pretty cool, the stainless steel ones are better though, depends how much you're willing to shell out for a grinder.

Jonny