Originally Posted by
Metallifan33
...I think I would get more "use" out of Di2, but again, I'm not sure if putting Ultegra Di2 on a 105 bike is something worth doing.
All of the SL frames are the same regardless of the groupset that was on it when purchased; there's nothing wrong with putting Di2 on that frame if that's what you want to do. You might end up spending a little more than if you would have jumped straight to the SL7 trim (factoring in the wheels, cockpit, etc), but do the math and see where it lands. Keep in mind that you can sell the 105 group to recoup some of the Di2 conversion or you can keep it for a future build.