There has been somewhat of a standard in the ef community for the past few years - 3.2 grams. Both Reggie and Buzzball list this as the standard around the year 2000 on their website. Miggle figures have always been around the 3.2 gram mark max. In the last 4-5 years, heavier figures have been produced which go above the 3.2 "standard". In fact, some of the first heavy figures ever made were not even designed for electric football use - they were designed for display. Coaches starting using them because they were great poses and they gained an advantage over lighter figures.
For me, I hate to see all of the hard work from the manufacturers who spent time designing and manufacturing figures to the 3.2 "standard" go to waste. The only reason to go heavier is to gain an advantage over those figures that weigh less. I still vote to use the heavier figures, because I love some of the poses and they add to the personality of the teams. But, I think you should have to bring them down to the weight that most manufacturers have been designing to.
My vote: 3.2-3.3 gram standard
beenutt