I play 4 tables of Rush daily to get my Iron Man points, typically 2 tables of $100 NL 6 max and 2 tables of $200 NL 6 max. 30 minutes max.
I don't think I have enough of a sample to say how I would do in the game in the long run, but I don't think I am very +EV... at least at those limits, the tables are just filled with regs and really not that many fish mixed in.
I'm sure it's softer lower and it's for sure a fantastic way to get your hands in and generate some nice RB.