Carbon Unit wrote:

"I have a triple and want to move to a compact sometime in 2011. I will have a different cassette on the compact than I would on the triple and this will give me approximately the same gear range....I will probably go with a 12-27."

So you're giving up a little at the low end, a little less than a 3 inch gear difference, enough that you'll have to work a little harder on the hills. And you'll gain a little at the high end. And you'll lose some gears that you would have with the triple. So why are you making the switch, to save some weight?.

The OP was extolling both the close-set ratio of his gears and the capability of almost never having to shift out of the middle chainring. But those are mutually exclusive concepts. If the cogs are close in number – e.g. 12-23 – then there are no easy gears for climbing in the middle chainring of a triple. And if the cogs aren't that close, then the ratio isn't that tight.