My sole piece of advice - spend some time looking closely at the gear combos you ride now and compare the ratios to where they would fall with a compact set-up. It may be that you end up on the outer edges of everything like I did and thus need to make some compromises.
I see the value of this. I just printed off some figures from Sheldon Brown's gear calculator (53/39T vs.50/36T vs. 50/34T)... and mulled over them as I ate lunch in the break room. It's not like i take explicit notes as to what gears I ride in... I just have an idea where I hang out most (i.e. on the 4-5 biggest on the 39 and maybe the 2-3 biggest on my 53... so you can see where I'm at). I compared the gear inches of what I have to what I'd get, and tried to place that into the range of useable gears (crossover and all that rot).
I've only had one good ride (and it was HILLY) since I went to the 12-27 cassette... so I suppose I should give it more time... BUT... as YCookMD said:
I think the compact setup is great for anyone who doesn't hang out in the 53-11 gearing a lot.
which kinda describes me. When I had my Felt in for adjustment, the repair guy noted that my small cog was 'awful clean looking.'
I think when I ride next, I'll take note of EXACTLY which cog/gear I am in when I am pushing high speeds, and if I run out of low gear on hills... then compare that gear-inch to what I'd gain... Ijust don't see myself doing 38 MPH on the flats or hammering 50MPH going down hill (it's too much fun coasting and screaming my head off... and hanging on for dear life!)
oh yeah...
BTW -- What does being older have to do with climbing ability?
goes more to the choices some of us more modest riders of middle age make regarding tweaking the rig to suit our needs. I've seen those guys in the white beards and red jerseys blowing me off the road... they are scary-good. ONe guy out by Paoli, on Observatory Hill... sheesh... but he was waiting for me at the bottom with encouraging words