There is really nothing more annoying than experiencing shoot-down. I spend quite some time (and paint) every week messing with these settings. I find I end up setting my dwell a little higher (15-17) than most people list for my setup (firebolt, NDz QEV and V****e board).
Would it be inappropriate to mention Anti Bolt Stick here? I find this feature significantly remedies drop-off/shoot-down and i think it maintains more efficiency than a higher dwell. (It's not on the stock board unless I'm mistaken)
I also encounter more consistent velocity with a good pinch on the paintball, for example yesterday I was chrono-ing dead on 300fps (+/- 3) with marbalizer and I think .679
At that gauge the paint was not keen on being blown out of the insert but the marker cycled better than I've ever had it set up since I started changing to aftermarket parts.