I've been wanting a Mangave for a looooong time. Basically since I found out they existed, in fact. (If memory serves, that was via Digging, though it's been so long ago that I can't be certain.) And now, thanks to a reader, I finally have one. Or, rather, two: one big one, one small one.
Both traveled fine, and I potted them both up with minimal leaf drop. The small plant didn't drop any leaves, but it's not growing new ones yet; the large plant lost a leaf or two, but is producing new ones already. Neither one had spots when shipped, because they'd been growing in shade and then spent a few days wrapped in newspaper in a dark cardboard box, but they both colored up once I put them outside in the sun.
That said, I don't think this is the ultimate full-sun coloration either. Depending on their particular spot, the plants north of the garage either get morning and afternoon sun, or afternoon-only sun. The Mangaves are in the first group, but there are still a few hours in the middle of the day when the garage is shading them and preventing them from reaching their full color potential, or something like that.
Regardless of the color (and honestly, whatever color they wind up is going to be fine with me), it looks like a pretty robust plant. I'm a little concerned about the potential size (davesgarden.com says they get to be 36-48 inches / 92-123 cm across), but if I let potential size worry me, my entire collection would constitute, like, three plants.