basebands
Ive ran the 00R the 01P and petes all in one all had wifi and 3g, 00R seemed to have more cell reception in the form of -db rating, but the 01P seems to have better 3G. You will find jumping basebands can dork over your phone, leaving changes to ANY baseband almost impossible. I had to backup, wipe, change roms then was able to change, then restore back to old rom. (baseband is seperate from roms completely)
if you loose 3G or some other function it is more likely to be from a bad download than it is from the baseband. A ton of people have done the two step upgrade 00R the n 01P with no problem. I have also gone back to 00R then back again to 01P. It just took more effort. I am currently waiting for test gear to do real in depth checking on exactly what the real differences are. More bands even better -db or speedtest.net results are not specific enough. I also noticed almost all links to petes baseband are dead.... the P3 second one's are not.