Spoke with Chris at SoundProfessionals today about possible upgrade to my 10 year old AT853 - we discussed the newer "U" series mics, as well as the AT943.
Chris noted that the capsule is the primary reason that the new 853's sound better, so I asked if the caps were interchangeable, which they are. So getting the U series caps with the old body may be something of an upgrade. He said it would definitely be an improvement, just not a dramatic one.
I'm gonna try it when I get my mics back from him after an overhaul.
Scott