I'll give my opinion, which ain't much.
I got a used VR4 for a very good price & couldn't afford a new IC.
The stretch hangs low enough, I worry about pulling up to a curb with my daily driver.
The previous owner of the VR4 picked up .4 over stock & another .2 when he went to a FM.
I've heard all kinds of overheating stories with the FM. I've found a radiator recore $150 & Ramchargers dual fan setup $80 work wonders in the cooling department.
Good luck with your decision, but with all new prices, I'd go with a FM.