Your Kestrel is 14 years old, and is a carbon-based life form. What's the market value? $700, maybe less? The cost of a di2 upgrade groupset is about $1500. What kind of used di2 bike can you get for $2200 plus?
As much as you are attached to the Kestrel, it's continued integrity after 14 years is not certain. Plus, you can get a newer design used bike that is designed for di2 and has it built in. If I were truly jonesin' for di2, I'd buy a used bike with it. That said, I'm still enjoying brifters and indexed shifting after moving from my old non-indexed Paramount. Not sure I'll be able to afford the new bike I want with di2 anytime soon, so I'll be sticking with manual Dura-Ace.
Last edited by WizardOfBoz; 07-31-16 at 08:12 AM.