I have no trouble at all operating my 150 Rotex in orbital mode with only one hand. So, I guess this is an individual thing. And this strengthens Joe's suggestion that you attempt to fine a place to try it first.I highly recommend finding a place where you can try them. I have the RO150 and in rotary mode it's a beast. You really have to hold on to it with both hands. In orbital mode, I find it to still be a two hand machine.