I am certainly no authority on the general concensus, but casual observations leads me to a different conclusion.
I can speak with certainty to my own experience; at least I think I can. Sometimes I do wonder, though.
With the Sprint OEM ROM, I did not experience the occasional and unpredictable issues (phone freeze) that I experienced with the WM6/WM6.1 hybrid ROMs.
Unfortunately, the down-side to the Sprint OEM ROM are the memory leaks. You can leave the phone on the end-table and the WM6 OS can leak memory, while aparently doing little to nothing.
Certainly, this does not conclude that the WM61 OS is the culprit. As jakdillard has stated, the issues may very well be with how an application, system enhancement or extension behaves on WM6.1, as opposed to WM6. If something that I load on my phone is having problems running with WM61, that's all the more reason for me to look for a WM6 alternative ... at least for now.
Best regards,
-boggsie