I would agree, and ironically I have dual SVS subs - PC12 plus's in each corner behind mine. It's a great combo when I want to thump and rock a bit I just add the subs to the mix with the SS8's X-over at 50hz.
I might be going to the SB13's if I think I can fit them comfortably behind mine in the corners. You get a year with SVS to upgrade and I might do it (no real reason I need to honestly, but I can't help but wonder if those woofers sound even better).
Will post a bit more detailed comparison in my findings between the two here shortly. There are a few other things that the E3's do that I have not heard in a sub 25k speaker ever.
I had both the PC12+ and SB13 in my house for a side-by-side audition. It wasn't even close, and that's not to knock the PC12+, it was great. I think I have a strong preference for sealed subs. Ported just sounds "woofier" to me, I feel like I *hear* it. I never feel like I hear the SB13, I just feel it vibrate my entire being when Gypsy Danger battles monsters on Pacific Rim.
Highly recommend you give it a try. My plan is to add a second, or three more.... unless they release an SB15 (fingers crossed).
Looking forward to hearing your additional comments about the E3.