I've encountered bubbles more often on Living Stereo shaded dog pressings than Dynaflexes. Of course YMMV.
05-05-08: Rshak
In addition to being flimsy, they were prone to other pressing defects, like "bubbles" which, if they could be tracked at all, sounded like a *dull thud* for 3 or 4 revolutions.
Looking at Dynaflex (and reading the original RCA ad copy), it seems like a scam, but I never had a sonic issue with a Dynaflex and some of the ones I have now sound particularly good.