Last season I sailed with a 6:1 with a 10mm or 7/16" main sheet with Ronstan blocks. This year I have 7:1 with 8mm or 5/16" sheet with Harken blocks. At the moment there's not a lot of difference, the extra purchase seems to make up for the thinner sheet size. I definitely haven't noticed the difference in the amount of sheet length which requires taking up when manouvering.