I'm using Daystate Rangemasters at the moment as my GP loves them. They all come out at either 8.4 or 8.5 so I don't bother weighing them as I get a total variation of 4fps at that weight. When I use exacts I do weigh them as one batch varied from 7.9 to 8.9!
With the GP having the chrono I was told by Daystate I must weigh pellets as the MVT function would constantly yo yo trying to self adjust. Some other GP owners I've spoken to don't bother weighing but they get a 12fps spread.