I've never bought a bike with Di2. I build my bikes from whatever components I feel are appropriate and I can afford and want to try, and I upgrade them from time to time. The first bike I put Di2 on was my summer Boardman SLS, several years ago, and I was immediately impressed with its accuracy and speed of shifting compared to the 105 5700 it came with (which was transferred to my son's Cannondale). I then built a Boardman Air TT with the same Ultegra 6850 Di2 groupset. Having the ability to change gears from both riding positions was great, but TTs turned out not to be my thing and that one sits unloved in the back of the garage!
My next foray into electronic gears was my Ritchey Break-Away, which has travelled with me to many parts of the world since I originally built it in 2009. I'd suffered a few times with problems related to travel - bent gear hangers, everything out of adjustment, the faff of reconnecting and disconnecting cables on every trip. The Ritchey is probably my favourite bike, and when Red ETAP came out I saw it as the answer to many of the problems of travelling with a de-constructable bike. It was some time before I could afford it, but eventually I splashed out - and it transformed the experience. The ability to not just not have to reconnect cables (Bowden or electric), but to be able to remove vulnerable bits like the rear mech without worrying about having to set it up again after it was replaced, made taking the bike away so much more pleasurable. The fact that the kit performs so well is a bonus, but it is (or was) an expensive luxury even compared to Ultegra Di2, and I won't be replacing it with AXS now I'm retired.
The last bike I built before retirement was intended for a LEJoG attempt (which advancing arthritis has unfortunately nixxed), and that uses Ultegra Di2 8050. The upgrade to the firmware which allows total customisation of the gear-changing logic was something of a revelation, and I've had many happy hours playing with the possibilities. I like the simple logic of Sram's setup, and I can kind of replicate that, though I've tried it and gone back to traditional Shimano mapping. The map that allows the kit to decide which mech moves when you want to change up or down (to achieve the smallest ratio change) is fascinating, as is the logic which prevents extreme cross-chaining - which is a bit of a life- (or chain-) saver when you're using an 11-42 on the back, as I am. The new Di2 looks to have extended the options. It's unlikely I'll be buying it unless I have to replace an existing set up, or decide to buy an off-the-peg bike with it, but I shall certainly enjoy testing it when I get the opportunity to borrow one from my LBS!
