Just to chime in, just my personal opinion.
I "broke my teeth" on Pepakura. Started with it and I gave up on it.
It's not that foam is 100 times quicker, but it does speed up the production process a lot and you see more "tangible progress" while working on it.
And for me, the weight (or lack of it) of a foam armor was also important.
You also skip the bondo/fiberglass step (and a lot of sanding) with foam which isn't something to underestimate, so it's my guess material-wise it's the cheaper method,
I'm 100% sure that me personally I'll have an easier time repairing a damaged foam armor compared to a damaged fiberglassed armor too.
As for details, i guess the determining factor is mainly how good you are at it. While I would expect pep-based material to win in terms of details, I've seen fantastic detailing on foam too by people who were much more crafted in it than I am.
Or better said, don't doubt that a halfway good made foam suit will beat the hell out of badly made pep suit.
As for comfort : well foam just sits very well.
Better said, first time I put on my MJVI armor with a compression suite underneath, it felt _naked_.
I've never had the chance to wear a GOOD fiberglassed suit in my life so I can't say too much about the comfort factor. I HAVE worn BAD fiberglassed suits on occasions (nothing cosplay related) and if something doesn't quite fit there, you'll feel it constantly like a pain in .... somewhere.
Foam by it's nature does not have that issue and is far more forgiving.
As for heat : the only part of the foam armor I had heat issues with was the helmet but hey, that's where fans are for and I know for a fact a fiberglassed helmet has the same issues when the design doesn't allow for natural airflow.