I didn't think of tri specific saddles, hm.

Right now, I have one bike that feels real good. It has a 74 degree STA with a 10mm setback post. The saddle, (an SLR), falls smack in the middle on the rails. I also have one frame that has a more slack seat tube that defaults about 3 cm further back. With a non setback post that puts me at, you guessed it, 2cm further back on the rails. That puts the SLR I'm currently using within half a cm of the end of the rails. I have a new Arione that I haven't tried yet that I'm considering putting in it's place. I'm thinking that I might like the Arione, especially with it's longer nose. but we will see.