Coming from someone who's run the 1-2 league here and tried running the gimmick league here until I moved it elsewhere.

These ideas are nice, but more difficult than you can imagine. If you really want to make a regular text league here work, you will need a LOT of advertising. A lot of AIMing people you don't know trying to get them to join. You haven't really done that with the 1-2 and haven't really needed to, but if you want a full text league to work, it'll be necessary. If you are comfortable spamming the internet with advertisements, making huge mags, and doing everything to hype the league, cool, but otherwise I wouldn't bother.