I've been perusing the Giant bicycle catalog and their high-end road-bikes have "integrated seat-masts", which basically means the seat-tube doesn't stop at the top-tube and keeps going up, serving as the seatpost. According to them it's "stiffer", but it's only an option on CARBON frames, which is why I am asking the following...
If one were to go with a custom steel frame, would this option increase stiffness and/or help with racing performance, or is going with a standard alu/carbon seatpost system a better way to go? Obviously you would still need a seatpost binder at the top with a severely cut-down alu/carbon seatpost to get the saddle attached to the frame (unless you welded the seatpost binding system to the seat-tube?). Seems like it would be more weight than a traditional seatpost setup?
I ask because I am considering going with a custom steel frame from a local framebuilder and I might as well go balls to the walls with the design and an integrated seatpost would look awesome!
I also desire a triple-triangle setup, and with an integrated seatmast, well...it'd definately be unique.