I'd read that going larger in the rear as compared to 14t front is less stressful on the chain over time, but that the higher cost was a significant factor. However, I found the additional $45 to be a negligible tradeoff for what's supposedly more mechanically sound.
Despite having purchased a 14t front sprocket in anticipation of swapping it out at my 7,500mi service, I sent it back unused to Ca-Cycleworks THREE MONTHS after purchase (thanks, Candice!) and went all new 15t/48t/DID chain instead. I immediately noticed more 'get-up-n-go' on the trip home, but I found the bike cruising smoothly at ~85 rather than ~95 as it did on the way there. I've also found the fuel light to come on right at 100mi rather than the 110-115mi at which it previously lit up, but that might just be me enjoying the new Termis/ECU.
In the end, first gear jumps up to 25 MPH quickly, but struggles to stay smooth around 30 MPH before smoothing out again around 35 MPH. Second and third are where the real fun begins until I really get on it in fourth and fifth gear to hear the song that begins at 6.5K+ RPM. I don't attempt wheelies, but I'm happy with the result.
