1) I wonder if it’d be worthwhile to remove the fighting defensively and total defense rules in a game using F&F. Given what can be accomplished with shiftable BAB, the latter two rules seem superfluous now.

2) In regards to gaining a dodge bonus to AC equal to BAB, it occurred to me that this may not serve the idea of nimble swashbucklers quite as much as it seems – this is because, as written, there’s no reason for a character not to also wear the heaviest armor they’re comfortable with in addition to the dodge bonus. That is, a wizard still won’t care for armor very much due to arcane spell failure chances, but a fighter will still be aiming for a suit of plate mail, since he can have that and his dodge bonus to AC.

I wonder if perhaps the dodge bonus should be limited via a suit of armor’s max Dex bonus value also (e.g. you couldn’t gain your BAB-based dodge bonus in a suit of splint mail (max Dex bonus +0), but could gain up to +8 of your BAB-based dodge bonus in a suit of padded mail (max Dex bonus +8)). The end result of this would be that characters would armor up heavily at earlier levels, and then gradually shed their armor at later levels). I’m not sure about this idea, though.

3) I’d definitely limit the amount of shiftable BAB by +5/-5, since that stops PCs from moving truly staggering amounts around at higher levels, which’d be prone to abuse (e.g. the fighter has the cleric cast a battery of defensive spells on him, then puts everything into damage rolls, with the offsetting AC penalty now somewhat mitigated).

4) The idea of a “martial pool” of multiple d20’s was laid down in Ire Games’s book Codex Martialis (they gave it that name). In that book, you gain one d20 per point of BAB, to a maximum of four. You’re then able to distribute those d20’s however you want to among your d20-based dice rolls each and every combat round. For example, if you only have one attack (from having, say, BAB +4), you can put all four d20’s into that attack roll, and use the best result. But then you have none left for saving throws, defense rolls, etc.

Something like that could be done with F&F, particularly since the PCs roll for everything, having active attacks (both physical and magical), and defenses (from both physical and magical attacks). It’s not a bad idea, but it’d have to be balanced carefully with the expanded uses of BAB already laid down in the book.