SVS or REVEL Subwoofer

SVS is primarily sold directly from the manufacturer. They can easily be adjusted and or positioned to sound less desirable than a REL.

The REL is a -6dB sub-bass speaker equipped with only basic crossover, 2 position phase switch and volume. Because its low frequency roll off is so dramatic it simply does't excite a rooms standing wave modes and can be located most anywhere and often next to the speakers.  

The SVS is an actual -3dB DSP equipped subwoofer. If its not located in the rooms standing wave mode it can over excite the rooms modes and possibly sound boomy. If the SVS is demonstrated in line with the speaker and the REL its likely out of its optimum position in a null. DSP is not intended as panacea for null or poor positioning rather to better match a speakers low frequency presentation.

If this looks to be the case and you find the REL to be more appealing to you, I'd suggest a dealer is pissing on your shoes.

Since you already have bass traps, I would recommend  the SVS SB 3000. I have a larger room (12 x 22) and after fine tuning placement, crossover and level by ear, the integration with my Dynaudio Emit 50 floor standers is spot on. I listen to a lot of two channel as well as home theater. The SVS can handle anything I can throw at it.

Room size does not have to limit number of subs (sonically) unless you literally have no room. My 4 SVS subs measure roughly 14" on every side. They're small, but the combined 4 allows them to be individually quick but collectively powerful. Not overpowering. Bass response is perfectly smooth and tight throughout the room. And my room is quite small.

Bought the REL S/510 today.  Thanks for all your help!

@rick_n 

Thanks for your detailed feedback.  You convinced me to pursue the S/510.  My dealer gave me a generous discount and I got 0% financing until 1/25!