I've been told by some that the 45 ACP is inherently more accurate than the 9mm cartridge.....several gun shops I visited recommended the 45 over the 9mm for competitive target shooting and hinted more towards a good 1911. That being said I really like the 9mm cartridge and would get another one in a heartbeat....however, seeing the P220 at a fairly decent price the temptation was just too much !
45 is like the 30-06, its just hard to beat it but these days for HD the 9mm does the job as well.
That said, the 9mm can be as accurate (my SP2022 is deadly with the factory Golden Sabre's though its an odd one to handload and I use the XTP for that).
I picked up some of the hard cast lead TC bullets. Not impressed, about the same as average FMJ for accuracy (does not make any difference for HD but I like to target shoot and accurate is the fun part)