The sizing is a bit weird, and you’ll hear a lot of differing opinions. My ASR-5a is a medium, and I’m 6′ with two 34″ legs. I’m happy with it, and it’s actually longer in the top tube + seat tube than my previous frame (a large commencal meta 5.5).
I test-rode a medium, and never got the chance to try a large. I don’t have any regrets with medium but I’d be curious to see what a large is like. The top tube is over an inch longer than the medium which makes me think it’d feel like a barge compared to mine.
I don’t know the answer to your question. To me the ASR-5 feels like a short travel (ish) trail bike with sorted geometry, plus it’s really stiff (even the alloy). How it compares to a 100mm XC race bike I don’t know, but at a guess I suspect the 5 is a more fun ride, at the expense of a bit of hill-climbing prowess.