I think the SB13 will hold its own against the F113, but the F113 according to Illk's tests will still out-gun the SB13 by 2-3db from 25hz down from the looks of it in terms of CEA max output. Be interesting to see how they compare compression wise.
A well written incisive review, Steve. Well done! Having sat in your room a few years ago for the subwoofer comparison tests (time flies!) I can appreciate the depth and care you took to write this review. It does shine in its quantitative analysis and commentary which makes a strong case for just how good a sealed sub SVS can produce.
One mild criticism is your presentation of the CEA 2010 comparison and any conclusions you can draw. While I know you did not carry out the requisite testing to derive the data, making a simplifying assumption of a linear 6db difference could be a bit of a stretch since the results can vary, perhaps significantly depending on frequency. It's not clear that the difference sub 25hz will be 2-3db compared to the FL113. Maybe it will but its best to wait for the data. It would be good to see SVS numbers in this regard. In any event the rest of the data/analysis is quite impressive.
Based on the rest of the specs/graphs the SB113 looks like one helluva fine sub and should give the FL113 a great run for the money. It sure looks like SVS has made a product designed to compete directly with the Fathom. Indeed subject to hearing it first hand and given the price differential and feature set, it may be enough to stop me from continuing to recommend Fathoms.
Anyway curiosity has now gotten the better of me. If you still have that SB113 it may be worthwhile for me to haul one of my FL113s up to your place for a direct comparison.
Also I'm withholding voting until I take a close read of the other two reviews.