[Lil' Lavery]

Very interesting concept, a nice simplified swerve concept. I think I may also try and find the parts/money to try and test it with Vex (although the bushing around the base of the drive will probably be hard to reproduce, I might have to prototype it without it).
Some thoughts to consider:
As it stands, this drive will have difficulty climbing ramps/inclines/large(r) steps. When the leading set of wheels starts to go up the incline, the drive wheels will be lifted off the ground, and the bot will roll back down. If you added some form of suspension to the omnis, this could possibly fix the situation, but that increases the weight/complexity. It's really a game/strategy dependent decision.
You're going to have to consider your wire runs carefully (but that is true for pretty much any swerve).
It might not be possible, but it would save a considerable amount of chain (and space that cannot be used to mount because chain is there) if the steering motor is moved to the central support.