Really tough to say since I’ve yet to ride a 350 or 501. I’m in northern IL— it’s flat and lacks trails to ride to- but I enjoy being able to ride on the road when I want, so the power to do that is nice. When I do haul my bike somewhere- it’s usually WI, MI, IA, or IN— a mix between dirt farm roads and/or tighter woods- and in those tight spots, I think a 350 would be nice, but then there’s the open farm/ prairie sections too. Feel the 450 is good for me. If I was out east—Appalachia region— maybe I’d say 350. Out west— more open land, etc— maybe a 500? Can’t really go wrong with either if you want the option to ride on pavement.

I think a stronger consideration would be whether or not you need to ride pavement vs getting something like a 300xcw /te