I own and ride both a V20 and S30, each with nearly identical components and wheels. The S30 is a little heavier and "feels" a little slower. But when I end my rides, average speeds on both bikes are nearly identical. The S30 "feels" slower because my head is a little higher off the road, so the landscape appears to be passing by more slowly, when in truth it isn't. Sometimes the S30 is faster than the V20, especially when climbing, because the steeper seat angle gives me a little more to push against. It sprints better than the V, but also has more wheel slip than the V. The S30 is better for social riding, while the V, for me, is a little more comfortable, so I ride it more (because most of my rides are solo). Both bikes corner well, but the V, with a 4 inch longer wheelbase and without suspension, feels more planted on choppy roads. When I travel to ride new roads, I load up the S30 because the more upright view gives me a better look at unfamiliar roads. The same goes for the winter months, when my after-work rides often end in the dark.
If, for some reason, I could only keep one, I would choose the V20, but not by much. Fortunately, I don't have to make that choice. It would make me sad. The good news is that both bikes are rad, so whichever one you have, you're in for a good time.