I ride a Cervelo P3 in a size 55, and was entertaining the thought of buying a Kestrel Talon or Talon SL for training. I know I need to get fitted and try the bike out, however my question is do the Kestrels run close to the Cervelo’s in size? My guess is I would be on a 55 Talon or a 52.
Just train on your P3. Performance requires specificity. If you don’t train hard on your P3, you won’t be able to race hard on it as you will have not adapted to that position. The Talon is a very different bike, using road geometry. When you flip the seat forward, you don’t get a tri bike, you get a road bike with a virtual steep seat post and shitty handling, due to an unaturally short front-centre. Now if you want the Talon set up as a road bike at 73 degrees for pack riding, then go for it, but still train on your P3 for solo/TT type training.