lots of dittos to what has been said.
as for my set up, if you look at my bike you see all sorts of speed blasphmey. as such, i am not slow but i will never be the fastest. and at over 200 lbs, well. it would just take too many watts. but, the bike takes me a lot of places and i can ride it for many hours straight day after day. for longer rides, i skip bottles and put my fluid bladder in the old style box.
i used to have a stock CB seat with some foam wedging and i liked it perfectly fine. i just like this better.
first you see that my bottom bracket is much lower than most. yep. maybe a little more drag than if it is higher in a much flatter hip/shoulder pocket, but not a ton. it is slightly higher than my hip. and i am not a small human. As such, that means my steer tube is not flat. yep, more drag, but then i use a curved slider to bring my handlebars down, leaving the bars just below my shoulders. i am not a straight arm rider, i am an elbows in and down rider. my hands are always on the drops, and my elbows rest on my torso. so i am not a torpedo as larry or bob, or any of the great fast guys, but i am pretty compact for as upright as sit.
i have my thor seat attached right to the frame. no rubber, just velcro and front tabs are shaved some to fit in between the seat ribs. two screws that go thru the seat and thru the frame. the seat angles are progressive with a couple foam wedges. 20 degrees, then 30 then 52 at the top. the neck rest is flipped over so it is like spring loaded pillow that fits below my helmet. ventisit pad is zip strapped to seat.
yes it climbs a little better than the flatter position, but since i outweigh most of the speedies, i probably still climb slower with more watts. but, what it really does is allows me to feel slightly upright but not punch a big hole, and it keeps my stomach acid in my stomach not my throat (i have a bad valve above the stomach)
sure you can shim a thor seat and a stock seat. but, i have always favored the foam, as it let me customize the shape, and let the seat itself be as firm to the frame as possible.
i have other bikes with 25 degree or lower slants. my slr, my tica, my apache, my old m5m (befor ian took it) each one has to have at least a little padding to raise my shoulders and curve my esophagus to keep the acid down.
feel free to play around with these things. the bike, particulary the Pre carbon is much more amenable to adjusting than people think.