Tough question. The NMT's don't have problems with the recorded content from the HD PVR or the HVR 1600 analog or digital ATSC/QAM captures but there are some problems with GBPVR 1.4.7 playing LiveTV in general that aren't related to the device itself.
LiveTV with the HD PVR has challenged GBPVR too but I don't think it is because of a problem with the NMT either.
Assuming a EGreat M34a is pretty much equivalent to a PCH-A100, then I say it works pretty well. I use the PCH to watch both live tv from both QAM (1600 or 2250) and HD PVR.
I don't watch a lot of live tv, but I do often start watching a recording that is in progress. I do this a lot for football games. I think from PCH perspective, watching a recording in progress is pretty similar to watching live tv. Once in a while the QAM timeline will seem messed up, but usually it works.
Windows 7 Premium 32-Bit, Intel i5 750, ASUS P7P55D, 4gb ram, ATI RADEON HD 4550, 5 sata drives, HVR2250, HDPVR, COMSKIP, PCH A100, EGreat 34a, VideoReDo, SA 4240HDC