My first thought is gag! Sorry, but that is a major change to the look of FR. Most users probably are going to freak when they look at that. :)
I especially always preferred FR continuous thread look, rather than the "broken into 20's" look of the Delphi's and others. It makes it REALLY hard to have a conversation because you have to constantly click links to read what post #40 was referencing in post #2, etc.
Maybe there could be an option to list the amount. Like "Show 100 replies per page" kind of option. Kinda like the Latest Post preferences. I do agree, I love FR format right now...if we could try to maintain the current format as much as possible all will be happy...