I believe the performance has improved with the x36 line on P25 systems, namely waterbury. I used to receive a lot of cutouts and distortion on my 396xt, especially in waterbury where the 3 sites were all being received. Now really the only time I have noticed any pixilation, the dispatcher usually asks the unit to repeat. this would indicate its an issue with the system/subscriber unit and not the scanner. The units still have their issues, but nothing that is earth shattering.
I have noted degraded performance on Type II systems. These have higher BERs than the 396xt on the previous firmware. I reverted my xt to the previous version of firmware. I thought performance degraded some. My 396xt would have BER in the single digits with the x36 in the 30s-40s. This was improved some by switching auto threshold to manual and adjusting the level to the system. I now have BERs in the 10-30 range. Mind you these levels are with full signal and being about 5-7 miles from the site.
I have not tested the unit on p25 phase II.