I got the Casoli one. Forty-odd quid plus p&p (a lot of money for what you get - light, a coupla wires, bolts and a piece of bent metal). Simple to fit, looks good, gets rid of loads of the cluttery bits, and there's no chance it's gonna foul my (7"x5") plate.
I got fed up with my original solution so refitted the ally bracket from the original but without all the plastic bits. Still relatively neat but very secure. The number plate light has beed epoxyed to the underside of the rear light. This means shaving off the lip on the lense cover with the two bolt holes. A bit of work but works fine. I'll take a pic later.
Occurred to me, when I was dismantling all the gubbins to fit the Casoli tidy, that it wouldn't be that hard to modify the original into something neater. Wonder why it didn't occur to the factory?