Ok, love to hear from Andrew or Ian on this, however there are quite a few very knowledgeable forum users too.

The room is 11.5 x 18.5 x 7.5
My M80 ar spaced 1'6" from the sides 9" from the front wall and 8.5' apart.
I sit 10ft away dead centre.

If you had $4000 - $5000 budget for subs what would be the best value.

4 - EP350
3 - EP500
2 - EP500 Front and a EP800 Horizontal rear
2 - EP800 one front one rear horizontal
2 - EP500 Front 2 - EP350 Rear

3 - SVS PB12 Plus
2 - SVS PB13 Ultras'

just to mix it up abit

Anthem MRX520
M5HPv4
VP160HPv4
QS10v4