Shimano Ultegra FC-6400 or FC-6600

[ATB24]

Hi folks, I was hoping for some opinions. I recently purchased a new frameset Cervelo Soloist Team and was thinking something over. My plan was to swap over the parts from my vintage Bottecchia bike (Shimano 600 6400 series) to this new frameset, the brakes work great as do the rest of the parts. I would just require a new bottom bracket to swap it over (old frame is Italian thread, new frame is English) The cranks have been working great for me and already spent enough money on the frameset.

Any reason I should ditch my current 6400 series and upgrade them to a 6500 or 6600?
Thanks for your thoughts,

 

[youhaditcoming]

Hello,

I would definitively invest money on the new FC-6600 Ultegra integrated crankset. Just order it with the british thread. To swap the rest would be ok i think.

Regards