which has a new RFI shielded all-metal body, smoother off axis response, better bass response, flatter highs, less self noise and more dynamic range.
Those a objective truths? Not that I'm offended by this product information, the combination of "not looking to sell" and the "information" looks funny.
As Brian notes above, RFI shielding is an objective truth. Can't really comment on the off-axis response. Better bass response, flatter highs, lower self noise and more dynamic range are all borne out by the specs provided by Audio Technica
and my own experience with the hypercardioid capsules from the old and new lines. It's not a night and day difference, but I like the new sound better.
That said, I'm not going to rush out to replace my other caps or my old AT853 bodies.
windorabug: The capsules are new but compatible with the old bodies. I have used capsules from the old line with my new U873R bodies, and my new hyper caps with the old AT853 bodies, with no problems.