On the flip side, I found the changes are noticeable (and not inconsequential!!) on the bikes I've had. It really depends on your bike. Looking at the photo, it looks suspiciously like the pads are more at the bottom end of their adjustment.
But why change? Though 27" tyres are harder to find and you do have less of a choice, you can still find them. Unless there's a compelling reason to, it might be easier to keep them, though I won't deny you'll be better off with 700C for the long term and for choice (and obviously if the current rims are shot -I notice they are 36h which is good -this is a good time to consider the conversion assuming you can do one with no problems). Geometry wise, I haven't done this change, but would assume the differences would be marginal; it would not be a concern to me.
Concerning the bike, I'm sure it would be fine for lightweight touring, though there might be some heel strike as it's not a pure touring bike, and the gears looks like they will be too high, so you *might* find yourself spending more money than you think you might (unless you are really going lightweight on the touring). And unless you have a real want to use 700c, as the previous poster mentioned, you might be better off waiting for a cheap old style mtb that you can convert with slicks (my neighbour has a Trek 930 he uses to tour on, and I can attest it's a very nice frame for that).
edit: I notice you are referring to an ad in Seattle. If you use caliper brakes, then without a lot of jiggery pokery and cutting into the fenders (don't ask) you will not have fenders on the bike. In rainy conditions touring, fenders are very, very nice to have.
Originally Posted by CCrew
27" and 700C are so close it's almost inconsequential. The several I've done we had to change nothing except the wheels, and adjust the brake pad positioning.
622mm dia on the 700c versus 630mm on the 27". Half that on the diameter which means the pads need to move 4mm.
Last edited by Nigeyy; 01-08-09 at 06:52 AM.