Warning: pure anecdotal content.
I've been using IF (14-16h fast each day) for almost two years now, of which almost a year with 531.
I have made substantial gains every since I:
- started on 531
- in doing so, almost doubled my workout frequency
- started eating more in general*
- started eating more carbs and protein*
I have NO idea how this would have turned out without IF, but I am very happy with my mass and strength gains. Whatever that means
To me, the IF approach does make a lot of sense, though. But truth is everybody is different and you should really just give it a try (for several months) and see how it compares. I plan on switching over to the more "classic" many meals a day approach at some point for comparison.
*) 1g per lbs of body weight for protein and carbs and 0.5g per lbs for fat as a minimum intake per day. Consistently.