Its funny some of the features or lack of that Mesa puts forward. My Big Block 750 is the earliest one with no controls at all to switch to the overdrive channel or mute the signal on the amp. You must have the footswitch which is included or else there is no way to access the overdrive channel or use the mute. This was soon addressed with the updated version but having a pull mute switch on the master volume control is really awkward.
I really like the Big Block but cannot get a Carbine out of my head. Turns out at this point, the largest music store chain in Canada has no M6's in stock at any of their 42 locations and have had them on back order since June 2009!!! M9's are available as the odd store demo unit but no new stock anywhere.
I wonder if Mesa is having a hard time keeping up with orders or if there is some problem with supply. I am right on the edge of trading in my Big Block for an M6 or M9 but I may not even be able to locate one.
I think you'd like the M6, but it is a different animal than the Big Block - more presence than the typical Mesa stuff. As fas as supply and demand goes, I think that has more to do with the economy in general. Musicians, being the ****heads that they are, typically don't have money to spend as it is in good times, much less when things are really crappy, so Mesa isn't going to build things if they think they can't sell them.