My favorite .22 (which also happens to be my favorite weapon overall) currently wears a Crossfire II 4-12x40 AO, and ive spent some time looking through several Diamondbacks. Glass quality and clarity is comparable (though I still give a slight edge to the DB for color and low-light performance), but build quality on the DB is a couple notches higher. Both are covered under the same warranty.
If it's a going to be a bench burner, mostly shot during daylight hours at non-game targets, the Crossfire provides more features you'll enjoy, such as AO and higher magnification. As a hunting rig, the DB would most likely serve for a bit more satisfaction.