Just got a Paradox so I thought I'd share some initial impressions.
It's a bit blinged out with the black acrylic paint, the cups look very slick now. The suspension band also helps out. Not that the TR50 was that heavy to begin with but the feel and weight distribution is much improved over the stock rubber arc.
On to the sound. I tried to go the head-fi route of song annotations and gave up fairly quickly.
Rilo Kiley - Silver Lining
Oddly the first song I chose to listen to with the Paradox resulted in its worst showing. There was an annoying emphasis on sibilants, so anytime Jenny Lewis sang an "s" I had to cringe a bit. The initial listen was on an Sammy S3, when I tried this song on the Lavry DA11 the annoying emphasis was subdued and more tolerable. Note: you do not want to listen to these on a weak portable.
LCD Soundsystem - Losing My Edge
An odd song which boils down to a basic synth beat and a guy bitching for a while. But by god was the synth beat rendered cleanly, the bass is much improved from a stock TR50. It's quick and measured without sounding too dry, it is dead neutral from low bass through to the mids.
One interesting thing I found about listening to the Paradox is that it falls in to the pattern of unforgiving unflattering phones where you'll easily hear any deficits in the recording. This makes sense thematically, given LFF's background in mastering. While I'm not usually too bothered by the meager dynamics in modern recordings with the Paradox their dynamic "flatness" became all the more apparent. I had to switch to a couple of classical recordings to let the headphone stretch its legs.
During some Beethoven and Grieg I was able to appreciate the crisply rendered attack, the distinct instrument layering and spatial separation as well as the noise limits of the recording. Overall the soundstage was a bit small without giving up any precision. In that respect the HD800 still gives a greater sense of awe and space to classical. However the Paradox mod approaches some of the "effortlessness" of the electrostats in that there's no bloat.
Also the treble sounds fairly well extended, unlike an older Yamaha stat I used for comparison.