Originally Posted by
Miller2
I currently run a 50/34 with a 12-27. I've had the opportunity to demo a Scott Foil and Fuji Altamira both with a standard crank during my usual weekly group ride. Now sure, there could be a placebo effect in place...
Unless you're spinning out in your highest gears with the compact, it's a placebo effect.
As you can tell using the link Merlin supplied, your top speed with your compact in its tallest gears and a cadence of 100rpm is around 32mph. With a 52-39 12-25, it's 34 mph.
Your speeds when using the big ring are nearly identical, as are the gaps. The real difference in the above scenario is on the low end.
If you are not mechanically inclined, constantly changing the cassette will be a PITA, unless you have two wheels with different cassettes.
I don't really see much reason to change.