GMATFocus is the math diagnostic, and I've used it personally. Excellent resource: good/representative questions, up-to-date, adaptive, very predictive of score, and it includes explanations.
If you are referring to the Paper Tests when you say "old verbal questions," it sounds like there is no overlap with the current (12th) OG, but I would suspect maybe a little overlap with the 10th edition.
Here's what the site says: "More than half the questions in GMAT Paper Tests can't be found in any other GMAT prep materials. Some portions of the paper tests can be found in earlier versions of the Official Guide for GMAT Review."
If there are any drawbacks to these, potential overlap concerns me less than lack of explanations and out-of-date format (both of which are openly acknowledged on the GMAC sales site, by the way).