The bit of line tying two single blocks together is how the Nacra 6.0's come factory - I've never heard of anyone having any trouble. I never worry about mine being even either. There's something like two feet of sail that continues down the luff track below the downhaul gromet.

There is only a single line that goes through the pulleys and ends in a v-jam cleat on the side of the mast. The other end of each line attaches to another double pulley that, through a series of sheaves and headbangers achieves 8:1 that is then doubled through the single pulleys on the sail to 16:1. Blah Blah Blah...the bottom line is that when rigging the boat, you only need to run two single lines through the two pulleys attached to the sail and end them in the v-jam cleat... want a picture? Let me know - I'm rigging the boat at my house this weekend for some setup checking.