No to make you second guess your decision on the Scott, but having rode a Scott SUB 20, I found that the ride was very rough even when the tires were deflated to 50 PSI. It seemed like every road imperfection was transmitted to the handlebars and I did not like the ride at all except when the pavement was smooth. I ended up trying to dodge every little thing which isn't always possible or sometimes dangerous.
Anyway... it's entirely possible that you prefer smaller frames and some people will prefer larger ones. For Marin Muirwoods 29er, the recommended size is 17" for 5'8". Having tried that though, I found that I had to put my butt way above the bars and I didn't like how that felt. I went with the 19" instead because it put the saddle only slightly higher than the bars; about 1 cm difference.