I have finished building up my Scott Plasma 3 TT bike with Ultegra Di2 and I'm really pleased with the results. Many thanks to Locutus, YahamaFX1 and others for their support and advice. I managed to get a great deal on a new 2011 Plasma 3 and went with the Ultegra upgrade requiring only shifters and derailleurs. I'm still running my old Shimano 6601 crank with Q rings and works great. For the "find" of the project, I managed to locate some really sweet rocker momentary (mom on -off- mom on) switches that fit perfectly into the ends of my HED extensions. With this setup I needed only two switches, instead of four, to mount in the extensions and I don't need to press, but rather just rock the switches forward or back to switch gears. Also, the Plasma 3 has a neat little opening above the bottom bracket covered by a metal plate. I drilled out the plate and ran my FD wires and Control box through the modified hole and mounted the control box on top of the bottom bracket. I have an internal battery and full internal cable routing, with only minimal cables and wires exposed in the back of my HED corsair bars. I bought Cateye switches to give me shifting control on the horns, but have not yet installed them. For now I like the clean look of this setup and for the events I ride I think they will have little real benefit. I'll see how it goes and if I decide on them it may be my winter project.

I'll post some pics below.