I like that league-style.
Advantages:
-easy schedule: 4 matches a month, get them played or default loss/draw. that s not too much for a month, everyone can play 4 games.
-holding zone: New teams join the ladder and can play. No waiting time till next season.
-monthly playoffs. Means good teams can go up the divisions w/o playing a complete season in a div, where noone can beat them and matches become boring. Also the other way around: a team who always looses gets bored, so they drop a bit till they found their lvl, they won t get fucked for a complete season. And playoffs are exciting (even more if there would be penalty shooting

-teams leaving: after 1 month u got the division at full strenagh again.
just my 2 cents