errrrrrr isn't the ref .5 technically an rocket ELT with a better tweeter? Heck, my money would be on the XLS. At the pricerange of $200, it's really hard to not consider the XLS. Sure they're not out yet, but the designer (dennis murphy) is a damn good speaker designer, and I dont think he messed around with the XLS.
Anyway, at the lower price range, i'd tend to stick with the amps listed. But if you wanna try the NAD, it wouldn't be a bad investment, as the resale value would be pretty much the same as you bought it for.
Good luck! and welcome to AC!