i test rode a pitch pro. im 5'9 and the medium was just about perfect or a little big for me. If your gonna grow more i suggest the large. If your done growing, ride a medium and a large if possible and just decide.
It might be a bit late now but here it is anyway, I'm 6ft ride a medium pitch pro and its spot on for all types of riding. I was tempted to go for a small because of the slightly shorter wheelbase, personaly i think a large would be too big but without trying one I cant be sure, if I were you I'd go for a medium if your mainly going to be using it for XC. Happy shopping!
5'6" here and on the small. I use it mostly for technical single track (not much climbing...) and a bit of dirt jumping / jibing. I'd guess a medium would be right for you unless your looking for a really tight, flick able trail bike.
I'm 6'2" and I just purchased a large Pitch comp.The medium felt really nice, but the large was just a little better for me. I also already had a cut seat post and put that on.
Go test ride an Enduro.. Same sizing, I do believe.