I don't have the Mesa DI, but do have a D800 and a Noble..
The D800 is great! It's small, light, powerful, and so crazy easy to dial in sounds.
But the Noble, to me is just sheer perfection. I can't break it down in technical speak, but there's some magic going on in that tiny box. I've ran it straight to the input of the D800 and it was fantastically stunning. Plus it doesn't get any easier with just two knobs and a switch.
Added bonus, it fits on a Nano, and powers six pedals, so no need for other power source.
Whatever sound you dial in on stage, is the sound FOH gets. And it's a beautiful thing. I'm debating going cabless and using just my Noble with IEM'S for the ultimate mini rig of doom.
You should check out the Noble thread here. Tons of great info and stories of use.
Some get scared off by the price... and I by no means have tons of disposable cash.. but I haven't regretted my purchase once. It blows my mind every time I play how something so small can sound perfect no matter where the knobs are...
There's also several YouTube videos, check them out as well.
Good luck, keep us posted