I did this race way back in 2013 and I was surprised by the amount of tt bikes on course. Personally I found most of the bike course was spent climbing or descending so I just had my road bike with aero bars for the valleys.
So I’d personally go with the sustained climbing which will likely incorporate a lot of sweet spot work to cover you for the sections of flat stuff. There were a lot of people going up the first climb like contador and then zig-zagging up the Alpe.
If it’s the same run course then I remember that having a solid little hill in it as well.
I’d also recommend giving yourself a few days up there prior to acclimatise. Even though it’s only 1800m I had a headache and nausea for the first 24 hours.
It’s an amazing race though!! Really well run.