You'd probably be better off using Vullaby if you wanted to use Murkrow to check Murkrow. Also, Nosepass now gets Rock Blast in BW2, so that might be better to run than Power Gem (going mixed isn't that bad with paralysis support anyways).
I'm probably the only person that really really loves Eviolite Archen, but it's SO GOOD at stopping LO Krow and the standard SubRoost set it's not even funny. The first set here
can shrug off everything bar LO Dark Pulse from Murkrow, easily stalling out Sucker Punch with Roost (and Stealth Rock). I've been considering running EQ in the last slot to hit a lot of common switchins to Archen.
Has anybody else had any experiences with Archen? It's far from a perfect Pokemon, but it's literally the only Flying-resist in LC that has reliable recovery, and I've had some good success with it.