I'd say stick with the B68- it's comfortable for you! Yes definitely get the non-"S" version- you will be able to slide it further back by about an INCH!
And at 110 pounds I'd say you probably don't really 'need' springs- you'd be introducing yet another variable into the delicate mix of having a comfy saddle.
So I vote for a B68 (non-S model). You will LOVE the added fore/aft range you get with it. I keep both of mine set all the way back....SO comfy and well balanced feeling for me!