I see no real advantage of DD's over the Weaver bases that you already own.
I've bought a lot of rings and bases, Tally, Leupold, and Warne mostly. I strictly use the Warne vertical rings now. Warne also has great customer service.
With your setup all you need is the rings, no bases which should save you some money.
Medium height should be good for you.
I normally buy mine from Opticsplanet.com and find a coupon code.