re: gear jumps, for sure, I changed my stock 11-34 to a 13-26, both 8 speed. A) I'll never be pushing a 48:11 ratio on the flats, by the time I spin out 48:13, I'm going darn near 35mph downhill... and B) 28:26 is plenty low enough to climb a mile long 8% grade, which is the steepest hill I expect to be doing any time in the foreseeable future (its the hill I live on, ok). by the time I get to doing more hill climbs, I'll be stronger anyways, and 28:26 will STILL be plenty low.
this 13-26 gave me MUCH closer spaced gears in the ranges I'm riding on the flats where it counts. I can use the big ring most of the time where everything is smoother.