Good idea Yogic, I think the introduction of too many modes and formats led to the level of player-base fragmentation that you describe.. there was already a choice between MP or SP (co-op), Equipped or Classic, Custom/Friendly or Ranked/League, Live or Async..
..these things were probably choice enough but then they were cut straight down the middle with a choice of mode, Chaos mode or Law mode.. and then cut in half again with a choice of Ranked/League or Duel mode..
..there are even more sub-sects between all those modes with things such as turn timer preferences, there's the option for 6 player games now to.. and often the forum tournaments and third party client tournaments offer a clearer/fairer scoring system than the in-game versions.
So it's quite hard to pool players into one particular thing and have them all agree on what a definitive format for the game is... That said, I'm always up for pretty much any kind of Chaos.
Custom 6ways are popular now (FFA, 3v3, 2v2v2 etc) ... Your suggestion is to focus solely on Live Ranked/League play yes? are we talking Live Classic Ranked 1v1 on these Fridays? or a mixture of 3way/4way Classic/Equipped (Ranked/Chaos mode)?
..I like the idea, I think it is important for Live to be the most active format. I probably can't make it tonight (which is another issue you might find, there's a lot of players that can't commit to blocks of live games at certain times).
I should be able to make it along on most occasions. I reckon you will get a good turn-out, the good thing about your chosen format is that there are no options to configure, the settings are default, no fuss, it's just click to enter the queue and play.. gl!