Please give me a hint comparing Hobart ProBlack 770753; Miller Black Dig Pro 256159; Jackson Balder Smart 37188 and Save Phace Black Ice Gen Y. Can one be picked as better for a beginner doing light TIG on thin CroMo tubing and some stick on some pipe framing. 4 vs 3 vs 2 sensors? 5 vs 3 vs 2 year warranty? The Save Phase stated no minimun TIG power. Are these all made in China? Gary Sinkus 352-258-3353