I was recently considering that very Vortex. You can do better IMO, but they do have a great warranty, from what I hear.
I felt the eye relief/eye location was very touchy on this Diamondback. Also it's a 2 piece tube (not sure if it's that big of a deal, but some say it is). The clarity, especially at full magnification, was just o.k.
The prostaff is a better option IMO. I thought the Trophy XLT were slightly better clarity wise.
I went with a Legend Ultra HD (see my post: Best current sales on scopes
) and it is lots better than the diamondback, IMO, and didn't cost that much more.
Also, Bushnell warranty is good. My dad had a old, fixed 4x rimfire scope go bad after many years of use. He sent it in, they returned to him a very nice 3-9x32 (trophy, I believe) scope that was much more than the old scope ever was.
I hope this helps.