really depends on the type of music you enjoy. 100.5" of surface area for two 8" 38mm combined one-way Xmax
113" of surface area for a single 12" 29mm one-way Xmax
That's a real close match between tne two for SPL. The 12" will feel as though it hits more deeply, having a lower Fs of 27.2Hz versus the 8W7 having an Fs of 35.2Hz, but due to the lower mass of the 8W7, the 8" will appear to be faster, and tighter. While I like the 8W7 myself, I'm very fond of the sound and feel of a 12" sub, and use 12" subs in both my car, and home systems. I'd opt to keep the twelve if it were up to me, but if you listen mostly to jazz, classical, or acoustic performances, you may prefer the 8" subs.