I had been chewing over where to go with shoes. The TCR 2015, includes 40 miles of gravel/off road as it follows the Strada Dell'Assietta.
Some good footage of this can be found on Youtube at https://www.youtube.com/watch?v=-gfo-OGUtng
On the recommendation of a friend who took part in the race last year and is also a cycle technician in Switzerland, I have plumbed for these: A pair of Specialized RIME MTB shoes. Principally because of the Vibram sole that provides for good traction should I find myself walking in the hills instead of cycling!!
Having looked at my old MTB shoes, I realise that I had chosen a pair a size larger than my normal shoes and this is well worth considering as specialised shoes come in a little small, especially if you're planning on wearing these shoes for 18-20 hours a day for two weeks.
After my 100 miles today, I am very pleased with them.