I use a 80mm stem with 17* drop, no spacers and a flatbar.
Bike sizing is a bit subjective, but I'm 5' 9.5" with a 31.75" inseam and on a medium with a 70mm stem and it feels a hair too small for me. I prefer a longer top tube than this medium has, but the seat tube on the large frame was a bit too long for my leg length.
IMHO the small would be ridiculously undersized unless it was for BMX, but like I said - bike sizing can be subjective. ;-)
I also ride a large Fezzari Signal Peak with a 60mm stem, for reference, and it fits me a lot better (could still use a shorter seat tube tho).