Small Visaton recommendation please

Hi guys,
I have a WAW or FAST or whatever the're called these days that consists of a Dayton DC300 and Markaudio CHR-70.
Minidsp, 4 chinese amps, xo 300Hz, 48db/oct (just because I can🙂 Didn't even test other slopes).


I find the chr-70 a bti harsh and beaming, so I want to try another, smaller driver as a FR unit, and I want it to be a Visaton, because they offer really a lot of good small fullrangers, and I can get them quite easily at work.



However, I can't decide between

FRS5x (people's chioce, so it seems)

FR58 (super flat, no published directivity pattern)

BF37 (kinda low efficiency, but should be sweet as a midhigh??)



The driver will reside in a 6l sealed, heavily damped chamber, probably not even important, since it will only ever be used at 300Hz+.
 
I don't mind some beaming, but isn't it so, that the bigger the driver, the worse it gets?



That's why I want to go with the smallest possible that can play 300Hz. And to play around a little, since all these drivers are sub 10€. 🙂