I use nock set knots..... just pieces of serving thread tied in a loop knot that serve the same purpose as a brass nock point, only without the weight in the middle of the string. You do pick up a little speed.... and its the net effect of little things like this that will make the difference between a bow shooting suprisingly fast and dissapointingly slow. I'm not a huge advocate of speed (I like to keep it under 280), but it allows me to shoot a heavier arrow at 280... see what I mean.

If, when tuning, I find I need to move my nocking point, I usually move the rest if at all possible first.... that has taken care of the problem for me and my customers 95% of the time. If the nock point is haneously too high or low on the string (in relation to the berger holes) then I'll move the whole works.