hi man,

Tough call - both could probably work. But to answer your question, if I had two bikes and was riding in the area you describe I'd probably favour the road bike.

But........I don't feel compromised in balance/control on my TT ( Cervelo P3) at all so its not really about that. Its more that TT bikes suit longer, flatter, more open roads where you can get up to and maintain a high average speed. With all those turns and tunnels you are minimising the value of the TT bike set up in my view.

I'd be more inclined to look at where you are riding, rather than what you are riding. Just a thought.

Heading into a tunnel at 25mph does sound pretty hairy to me too BTW.