Tricky question. I suppose that if the pre/pro or reciever's auto EQ works well enough, the SMS-1 becomes redundant. If it still needs some maual tweaks in the bass, the SMS does that very well.
I don't have any auto EQ, but I would think that I would place the SMS between th pre/pro and the sub, run the auto EQ, then use the SMS to see how flat the response is. If it's to your liking, sell the SMS. If not, you can use the SMS for your "second degree smoothing".