I was looking over your results which look good, and thought I'd offer a suggestion. I see that you have boosted 3 of the filters 5-6db. Despite how it looks, boosting nulls is rarely beneficial and such large boosts can add ringing, and make for very uneven bass outside the sweet spot. You may get better overall results by restricting your boosts to no more than 3db. In other words you may get better sound across the room by giving up some linearity at the microphone placement.
Also I note that the EP350 rolls off at 28hz anechoic so boosting below at 20hz doesn't give you much output for the cost of additional harmonic distortion. An alternative would be to keep experimenting with placement to see where you can get more output in the low bass then equalize.
SMS is a terrific tool for the price, even though there are now newer products which supposedly address time domain (ringing) as well as frequency response.
All your points above are correct. One of the "warnings" velodynes gives is to try to restrict boost to +3db on any fq. However, this mostly applies when you attempt "stacking" of fq. But again, you're right, going above 3db is not ideal at all.
After more experimenting, I did back down the 20hz boost to +2db for the exact reason you state. I was worried about forcing the sub amps beyond their capabilities on both my subs, PL-200 and the EP350, to prevent damage to the subs.
Tonight I am going to try to eliminate the boosting as much as I can. As you suggest, I need to move the subs around some.
I'll try to get some more results posted soon, so let me know what you think then.
This thing is so much fun, I can't stop "fiddling" with it
Oh, one of the things I couldn't figure out is why it boosted 100hz so high when the xo is set at 80hz. Even when I backed it down, it didn't hurt the flatness of the curve much at all. Thank goodness this thing has full manual control.