I don't see a need to match subs to other speakers usually, unless you are trying to match the finishes (as with veneered speakers, for example).

Having owned the smallest SVS tube, it's anything but diminuitive - my wife far preferred the LFM-1 to the 25-31PCi for appearance because of this, even though the LFM-1 takes a little more floor space. If something that takes up as much as 24"x24" of floor space is an option worth considering, I'd say that there are a lot of good options out there.