Nick, I guess I should make some enquiries and find out exactly what the differences are!
The facts I know at the moment are:
Alpina 4.6 engine
Much bigger brakes with ram air vents in front bumper for cooling
Carbon fibre hardtop
Colour scheme. Mauritius Blue Pearl/Titan Silver
Things I've heard but not confirmed:
The cars were not built going through Morgan's normal production line but separately by a small team
3 of the 11 (that I know of) also have a soft top. Unlike the S2/S4 cars, the soft top is not installed under the hardtop but instead of.
1 of the 11 has a slightly wider body. I haven't measured it to give exact size difference but I have seen it and would appear to be perhaps 1 or 2 inches wider.
The ones with black wheels are faster!!! :-)