As far as I know, the i50/p25 switching in the UK has only been seen to cause stuttering for WMC users. In my case, 7MC is badly affected, but my TV receiver is not. As I understand it, the improved image quality and compression ratio provided by MPEG4/AVC/H.264 over MPEG2, means the decoder has to work much harder to output the data in real time. So it seems likely that a software decoder may be vulnerable to stuttering where a hardware implementation is not.
However, it's also possible that the Microsoft video decoder in MSMPEG2VDEC.dll (which supports H.264 despite it's name) does not handle these frame-rate changes properly. I'm willing to throw hardware at this problem (if I only knew what hardware), but AFAIK, neither the BBC nor Microsoft seem interested in providing support.
I believe a later version of MSMPEG2VDEC.dll ships with Windows 8, so I wondered optimistically if any 8MC users in the UK have seen stuttering on BBC HD terrestrial (FreeView) transmissions?