It's been a long time since I heard any DefTech speakers (looked at them some before I bought my Paradigms back in 2001), and the only ML's I've heard were Aeon 1's at a friend's house. The Aeon 1's were nice - I'd probably have to rank them above the DefTech BP20's I demo'ed (typical DefTech bipole tower, but one of the older models without the side-firing powered woofer). Both speakers are going to be fairly placement-sensitive (the DefTech's because of the rear-firing drivers and the ML's because of the electrostatic panels) - I assume your space will allow the speakers to stand out a distance from the walls to give them room to "breath?" Either way, the best approach to speaker shopping will always be to let your ear be the judge. If you can swing an in-home demo (maybe a weekend loan or something similar), that'd be the ideal since it removes the variables of equipment, system setup, and acoustics at the store. If your only venue for listening is in the store, take a good stack of your own demo material, see if you can do some adjusting of speaker placement at the store to deal with poor setups (as may have been the case with the Vistas you heard recently), and try to spend some quality time listening - as you may have already done. Hopefully that will help you make the decision.