Making 6.5 free would be silly, since it is still used by a fair amount of owners. Just look at how many online leagues still use 6.5.
But then again, as a commish of two 6.5 leagues and thinking of starting another one, having it be free would likely increase the number of people using it, so go for it!
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-Chris
CIBL - Commish - 95 & 96 World Champion St. Louis Cardinals (82-97); Arizona Diamondbacks (98-present)
UBL - 39 & 40 World Champion Atlanta Black Crackers
MCBL - Commish - 50, 55 & 59 World Champion New York Yankees