SD is correct. The surf package in the X30 comes with factory plumbed sacs in the corners that sit on the hard tanks. The sacks are 450's. I swapped those for some 600's that I had from my MB and those totally fill the compartment. I'm not sure if it will make much of a difference but I did it because I had the 600's and nothing to do except wait for the rain to stop.
The total ballast in the MC is nowhere near that of the MB. I think I'm near 2,000 lbs total, including the added sacs. From what I've read and what we did when I tested the X30 before I bought it, that is enough to have a good surf wave. I may plumb a bow sack but that will be next winter after I try this for a season.
The MB's have the advantage far and above the MC when it comes to storage. My 21 TC had more storage than my X30 has. I also really like the way the compartments are designed in the MB over the MC because everything is below the floor and the floors are flat. The MC floors are not flat in the compartments and storing stuff in there and working in there is a PITA compared to the MB.
Yes, I'm one of those dumb-a**es that chose a profile name based on a boat model that I had. That's kind of like getting a tattoo of your girlfriend's name on your bicep when you are 16.