I see this is an old thread, but I've heard both of the single-woofer Synergy models before on my buddy's setup - they both work well as strained-budget options, but in different ways. The floorstanding speakers come off as really bass-y coming out of a S.E.X. which can work as a pseudo-2.1 option for combined music/ht usage, but can also be overbearing for certain types of music. Would be nice for an apartment/condo all-purpose media center / listening station as long as you don't have irritable neighbors.
Otherwise, the bookshelves work nicely to start. Will sound unimpressive in the first 5 minutes while the amp warms up, but after that, output optimizes somewhere near 12 o'clock for pretty good volume in a small space. Distortion starts to come in noticeably around 2:30, 3 o'clock. Just a little bit more power than the S.E.X. amp would probably be nice for bringing the best out of the bass & treble.
Hope that helps.