Another I am looking at is a Diamondback over at Performance (they have 30% back this weekend in points). Spec and size wise, is this pretty comparable to the Marlin 5?

Diamondback Overdrive ($399 and then get $120 in points credit at Performance):
Diamondback Bikes - Mountain Bikes - Overdrive

Marlin 5 ($459 at LBS):
Marlin 5 | Trek Bikes