I have used Hypertherm plasma cutters as well as others in the past but can't remember if the Thermal Dynamics is one of them or not. Both units are good names and either sould be a good choice. Regarding duty cycle you can easily compare the specifications to determine where they stand. Important are piercing rating and material thickness capacity. Most people will try to by as little machine as they think they can get away with to meet their needs only to find they wish they'd gotten one a little bigger. More than likely either of these units will be good choices for home/shop use, bigger than most would choose. I'd be happy with either one. Maybe buy both and let me keep one at my place for you!!
Probably the biggest thing to look at is the price and availability of consumables, which more than likely you will go through quicker than you think. Most users of hand held plasma cutters really trash the consumables by dragging the tip on the work or holding the tip to far from the work simply because they don't use them often enough to get good at it. The tips can erode pretty quickly if not used properly. You'll probably want to put some type of moisture trap in the air line too. Wish I had either one.