Would you buy a used 2012 bike (TT in this case)?

Locally, there is a pretty decent deal (I think) on a 2012 Cervelo P2. It’s the frame size of my other 2 Cervelos (R2 and S1, yes it is old), upgraded to full Ultegra 6800, and presumably an older version of these wheels. For reference it is selling for hundreds cheaper than a stock 2018 P2.

Job one will obviously be getting it professionally fit, especially considering I’ve never even sat on a TT bike before. All of this is for duathalon (sprint, looking at moving to standard), which I was FOP’ish with this year on my R2.

Has frame technology improved enough since 2012 (say for the P2 specifically) that I should just spend the money (likely $1500 more if I want decent wheels) and get a newer P2? Or should I just go for the deal, save some money that can be better spent elsewhere, and if a get a good couple of years out of it that’ll be fine?

Things have improved, both with aerodynamics and comfort, but it’s all marginal improvements on what is otherwise already an excellent bike. Whether that’s worth the extra money or not is up to you… the difference between a 2012 P2 and a 2018 P2 is going to be inconsequential compared to a good aero position and a good fit.

Agreed. You can do a lot worse than an old P2 that’s for sure. You’ll easily get a couple of years out of it and with a good selection of components (which it may already have?), cockpit especially, will match or better many newer bikes.

An upgraded old P2 will I’m sure be faster than a stock newer P2, assuming you have a good fit and that’s where I would spend my money.

Agree with the above as long as it fits it will be a great bike. In my opinion TT bikes tend to be well looked after so the age shouldn’t be a problem.