I had a quick ride on a Surly Disc Trucker today. The ride felt really good. I was only on it for a couple of minutes though, so it's hard to tell if it'll be comfortable during a long trip. Unfortunately the bike doesn't come with any racks or mudguards, so a full package was quoted to me as costing 1500GBP. Ouch. Something to think about.
Disc brakes were on my list of wants for a new bike, but now I'm not so sure. The non-disc-brake version is about 200GBP cheaper. The one I rode today had particularly thick tires, and replacing them also cost extra.
The thing I disliked most about it was the brake placement on the handlebars. My old Giant Great Journey had two brake handles for front and rear each, one mounted on the lower area of the handlebars (usual place for racing bikes), and one mounted on top (the usual place for regular bikes). I hardly ever assume the racing position when touring so I quite missed them.
Customizing parts should be more or less possible, but will quite likely end up in an even higher cost. Is a bicycle really worth that much to me? Perhaps I should just import another Great Journey..