I would say you get a superior grip from the WARN pattern in the center compared to the almost plain Valox on the 580
The 581 is a big step up in terms of materials used on the handles and the blade, that's why I like it so much. If you decided that the G-10 on the 583 wasn't grippy enough, you could always use 100-200grit Sandpaper and roughen the surface a bit
I'm really curious as to what the grip on the alunimum bolsters is like compared to the G-10 handles? I'm going to buy another 58x, I just want maximum grip.