10's that are 10.5 outer & 9 inner?
 

Besides the JL 10W6v2, what other subs have an outer diameter of 10.5" and a cut-out of 9", so that the mounting ring is .75"?

Also, does SD*xmax matter much in a direct comparison?

like pretty much most 10 inch subs

^ yeah, that sounds about right. Give or take.

Most are over 10.5" diameter with a .65" mounting ring, and that doesn't help with a flush mount nor with keeping to within 21" for 2 10's.