I've had the CG980 a little over a month. I'd been wanting one of the MBs ever since they came out, read/watched everything I could about them, even convinced my sister in law to buy the 560. Then a few weeks later saw the 980. Hope she wasn't too miffed that I told her to get the MB560 because thats what I would get, then I got something else! But honestly I think they both have their pros and cons. I would likely be happy with the 560 too.
As much as I like the 980, there are times I think I should have just stuck with my
Akorn, or perhaps a larger Kamado, coupled with a temp controller. Can do low and slow, smoke, fast and hot, and sear...although transition time may be slower. Miserly with charcoal consumption.
As someone said above, the MB and CG both have a voracious appetite for charcoal.
The CG has IMO a very heavy durable metal construction throughout.
The CG has a heavy duty removal hopper, essentially triple walled since the 2 walled hopper sits inside another liner. Not sure it provides any significant heat efficiency though. I have pulled it out to remove charcoal once (some mesquite lump that I did not like) but not sure that its something I would do very often. It does seem very durable though.
CG may have an issue with the fan flap (not for me yet), MB may have switch issues.
The CG manifold is heavy and massive, porcelain coated, but easy to take in and out. I'm not concerned about longevity. Because there is a drip shield, I've only had a few spots of grease on it so far.
The drip shield is a nice feature but because it is slotted its difficult to foil. So I don't, and instead just scrape it pretty regular. Seems to be working out fine. I scrape the shield, pull the manifold, and scrape all the debris and other stuff down into the grease pan for removal.
As mentioned there is no room to slip in another drip pan, while the MB design lets you move the meat up and add a pan on the main grate. That would help with messier cooks. I did two butts on the 980 this weekend, no pan and I'll just scrape to clean up.
The MB adds the griddle and rotisserie options, nice if you want them. Perhaps CG or someone else can some up with a new manifold for the CG that would work like the griddle on the MB.
Long story short, as mcokevin said in the first reply, I think either is a fine choice. Pros and cons for each of them. I bought the 980 but nothing in my opinion that says one is NOT a good choice.