Idepending on the tree I one hand a fair bit. It tends to be an on the spot decision based on what I need the wood to do.
A few years ago I had pretty bad tennis elbow. Probably from one handing the 200 all the time. I made an effort to two hand the saw wereever possible. Tennis elbow cleared up.
I took two things from that.
1 one handing a saw puts more strain on ligaments, tendons and muscles.
2 I bought a 150, had it timed and modded. Makes one handing much easier. ;)