I bought a bike with a compact double because I got a great deal on craigslist. It replaced a bike with a triple. I found that I had lost my bottom 2 lowest gears. I live in the Santa Cruz mountains, and some of the hills are either very steep or very long or both. When I went to get a bigger rear cassette (for a 10 speed), they (Shimano) said there was no such thing. It turns out that a company called IRD does make one. Pairing that (12-32) with a long cage road bike derailleur that was meant for 10 speed works just great (not a mountain bike derailleur that is meant for 9 speed). Anyway, I got my low gears back and now like the compact double better. On the triple, it seemed that I was either riding on flat or downhill where I was in the large front ring. Or it got very steep and I needed the small front ring. It seems that I almost never used the middle ring and it was just an extra step to shift through it. the double with a bigger rear cassette seems to be the best of both worlds. Perhaps you could special order your new bike like that instead of having to pay to change it out later.