Out of curiosity, who did you check with about component sizes? I ask because last year's Vaya had the component size info included on the build spec page
http://salsacycles.com/bikes/vaya11/ and the sizes listed match nearly perfectly to what you usually ride. I wonder if someone quoted the wrong specs to you, maybe double-check, all of those parts seem awfully small for a 57???
If the sizes quoted are correct, check the spec on the 58 if you think you can live with a 1cm longer TT. If not, maybe your shop can help you with pricing on the correct size components and you can usually get a decent return on the OE parts by selling them on ebay.
From what I've seen on here, many others have bought frames and built as they pleased. The complete price is just too good of a deal, and I've played the expensive and time consuming "custom" build game too many times already. FWIW, my 60 fit perfect out of the box and the only thing I changed was the saddle; the stock salsa is not too bad and it currently resides on my town-bike, I just like the WTB SST for any sort of distance. The only components that I'm not 100% happy about are the BB5 brakes, I would have gladly paid the extra $50 to get the BB7s as stock. The brakes work, but have to be a little looser than I would like to eliminate pad rub; the way the pads are attached to the BB7s eliminate this problem.
Good luck, the bikes are great! This is by far one of my favorite bikes that I've ever owned, there are many very good reasons why they are almost all sold before they arrive in-country. I waited 4-5 months for mine...and it was totally worth it.
