I have been running a 252 on a cell phone and CORS station for almost 3 years now.  The 252 has never given a CMR% reading.  There is something about the 252 that does not get the CMR% from the cell phone.  I have a 332 in my sprayer running on the same cell system and same CORS station.  It reports CMR% everytime.  The problem is in the 252.

As to your statement about WAAS and RTK, I agree.  Accuracy is addictive.