Right, you remove main tray, and additional tray that sits up against the rad. Then anti-roll bar bush mounts and let it hang out of the way (without hitting your head on it loads of times like I did). Only other thing was unbolting the power-steering cooling loop mounts, and pushing that pipe out of the way.
Indeed the new stat seems to be plastic rather than Alu, but all fittings / angles are identical to the original part.
I was interested to see that the pump impellor is still plastic like the original... I thought I heard that they went Alu on that.
I'm wondering whether to have a peek in the old pump before I return to BMW for my surcharge back... I'm guessing something electrical failed...