Oh great!
If you have any feeling at all that you need to move your saddle further back- then just go ahead and GET the non-S version. It made a HUGE difference to me and my weight balance to get that saddle back another 1-2 inches. OMG it was so much better- I could get some power behind my legs pedaling for once. I suspect you will INSTANTLY love it as I did. If not, you can just send it back. It's not for everyone, of course, but from what you say I would suggest trying it.