My first guitar was a GIO, and I first did use extremely low action... about 1.2mm - 1.5mm. Later, I felt like I was doing myself a disservice: alternate picking became awkward, bending became impossible, and my pinky was flailing at every string it could get to. Sweep picking became near impossible due to my inability to roll properly. The only thing that improved was legato. So I raised it to normal medium: 1.5-2.0, and then 1.7-2.3 (and I really like this one), then I found out that the further up I go, the thicker I sound. I went up and up until I stop and say "this is getting out of hand".