The Hobart 135 120V machine has proven to be a very good choice for lots of tasks, and especially good for easy sheetmetal fabrication.
The heat/voltage settings for the best results will vary with the operator's skill and experience levels, most likely. For .025" wire and C25 mix (I'm not that skilled at moving fast, so the lower settings of 3 and 2 are proving to be completely adequate for lapped joints, and tacking butt-jointed 20 ga. sheetmtal. Even the lowest setting of 1, may be useful for
Using the Hobart 135 with some Lincoln SuperArc L-56 ER70S-6 .025" wire and C25 mix (75%Argon/25%CO2) with new 20 gauge (.037") mild steel, there were reltively few changes that were required. Connecting the gas regulator, changing polarity and the wire drive roller and with a new contact tip, made for a simple change-over.
For however many years I've been using this Hobart 135, all that's been used has been flux-core wire, with essentilly no problems. Clean, spatter-free welds are definitely the best.