Which Groupset?

Indeed, I've got Di2 on my S2 so I'm aware of the pros and cons. The only thing which is stopping me going and Di2ing the TT bike is that I've never changed from the big ring on it yet (more of a reflection on the lack of elevation changes round here than my mighty powah) so the front shifting benefit is a bit hypothetical.

I train on mine quite a lot so the front shifting is a small benefit. The fact I don't have to bend my wrists around the front to force it into top gear is nice. I've got my first race on it on Sunday so I'll see how it goes 'in anger'.