I heard people mentioning me so hear I am!
Bimmerdriver, you got all the correct answers already in the responses above. (thanks to both of you) though I would say that my tunes are more aggressive than the ones from California, aspecially because they don't have proper 91 octane gas there. And on top of that, Dinan tries to sell you a lot of hardware so you need stage 3 or 4 to get software similar to what I sell you right away.
With a slightly raised rev limit, you would just use it occasionally, not 10 times a day so wear on the motor is not increased. If you buy my software, you have 10 days to try and I'll restore your car back to stock if you feel that it does not work as expected for you.
And if you really want to know if there is some non-stock software in the car now, I can tell you by reading the ECU and comparing it to a stock file. Last September I tuned an E39 M5 and they were told there was Dinan software in there, but it was completely stock.