This is a crazy good price for this head! Don't be afraid because it's "only" 300 watts, and you think you need the 600 watts of a M6. I've had both side by side, and the M3 gives up very little in power to the M6. I'd be willing to bet that most players who have a M6 don't come close to the limits. The M3 will outdo all the 500 watt micros, IMO.
Here's a Bass Guitar Mag review by Chef, with some M3 to M6 comparisons in it: http://btpub.boyd-printing.com/displ....php?id=616950