I would be MORE than happy to pay for a PRO version that was multisite.
Some useful multisite additions would be:
1) The ability to share the league across a network of sites so that the league does not have to be set up for each individual site.
2) The ability to make some leagues not to available on multisite
3) Assign users network users as managers for individual or multiple leagues
4) The ability for each site to flag their team as the home team.