I talked with Nick about this yesterday. He said he'd received a lot of feedback regarding this and that he'd actually contacted Cervelo about it. There is a *chance* he'll give more details about the process soon. It does void the warranty, obviously.
I'm not 100% sure the above warranty statement is correct. I have seen this build too, and called about it as well. I was interested in Di2 on a P3 and was concerned about the routing scheme because it was not in the original design.
A GENTLEMAN AT CERVELO, told me that they had heard of it being done, and that it would require drilling some small holes, but that if done by a Cervelo dealer/approved warranty center/repair shop/whatever you want to call it, that the warranty would stay in tact.
They went on to say that the main concern was not the holes in the frame themselves, so much as it might be the futility of the holes. Reason they gave was that when the carbon lay-up is kicking off in the molding process/cooking process, the resin needs to and does flow. In may be that it flows "inconveniently" and "seals up" or otherwise obstructs the potential pathways of the cables that need to be routed. He said it would vary from frame to frame, and the only way to know was to drill baby drill and find out. He was specifically concerned about the chainstays.
Anyway, I love the P3, hate the look of the P4 and had (at the time) basically decided to go P3 with a Di2 build (because I had that group already, but no bike). When I went to visit my local Cervelo dealers, I did not get the sense of confidence that I would need to have in order to trust them to go drilling holes in my dream bike. The only builds I saw that I would trust were the one shown here, and another (I believe) in either CA or AZ. I live in Florida, so scratch that idea.
So, here I am, no (new) bike yet, race season upon me, waiting for my shot at a P5 frameset that will take the Di2 without batting an eye.
"What do you mean your running shoes don't match your bike?"