The PGM IV is definately not an issue, with the correct card its as good as a HRC pgm. My track bike makes good power and is using a PGMIV.

I was however considering taking the PGM off my MC21 with the loom and putting it on my track bike so as to free up the PGM for a future rebuild of the MC28SP. Then again its probably almost beyond a rebuild and it will be cheaper just to go to fastline and buy a 28SP.