The rider interface bits of our mountain bike frames are pretty much the same shape, and certainly the same top tube lengths, so the only reason I can see for you going for a medium is if you run a pretty long (80-90mm) stem on your Soul and wanted to drop down to a 50-60mm stem on the Hemlock for more responsive steering with bigger forks. Other than that, I’d stick with small. The standover is the same on both frames, but the medium seat tube is 40mm longer so you’ll not be able to get your saddle as far out of the way on the bigger frame, if that’s a consideration. Oh, and we’re out of stock until June when the next lot arrive. Feel free to pre-order though.