I have little experience with TTTF, having just recently used it for the first time. But I have a few years' worth of basic experieince with turf type perennial rye grass. And I can say with confidence that TTPR is an aggressive tillerer (if that is a word). In my experieince, when PR thins out, it can (and will if conditions are right) tiller readily to fill in. Some of this tillering (with regular lawn variety TTPR cultivars) appears to be pseudo-stoloniferous regardless of what the RPR guys say. I say this because I've noticed it's possible to divide and replant (without too much pulling) TTPR plants that have tillered. (I've done it successfully.)

A single TTRP plant that has tillered can have ~50 blades in my experience.

Now here's the question. Does TTTF tiller to the same extent as TTPR? E.g. 50+ blades per plant if the lawn is allowed to thin out?

(And as far as dividing goes, TTTF should in theory divide better than TTPR, since it's rhizomatous.)