The Diversion 165 sounds interesting, with a range from about 10 amps to 165. I have never even seen one, but the literature sounds good. I use dynasty units which give an amperage range from about 5 amps up depending on the unit... 200, 350, 700.
For HK stuff you do not need a water cooled torch. For thin sheet metal you dont need a very large tungsten.... 1/16th does just fine for thin stuff.... I have used an .040 tungsten for instance just because it was already in the torch. Doing nice TIG work takes practice and a good understanding of weld technique. You need to weld the edges of the plate together, site base to the receiver, and of course the trunnion .....all relatively easy for an experienced hand, but quite difficult for a novice.