Yut, I heard that it can be hot for seedlings and young plants but it should be ok once you transplant into the final container. I don't know how much perlite FF uses in their OF. I don't use any soil mixture, I use promix HP = (75% peat moss, 25% perlite, inoculant, dolomite lime) To this I'll add 25% compost and a bunch of other active nutrients.
I would think that FFOF should be loose enough but if you don't think so extra perlite shouldn't hurt anything.