Just read all 7 pages, but it looks wicked. But price wise, you're probably looking at about £7k - and its only ever going to look decent on immaculate cars.
Not an alternative to a respray (could hardly go using it on a battered old MK2), but as a reversable respray - wicked!
And to answer the V5 question, you would obviously have to declare the change. My car was green, but I sprayed it black - just because its green underneath - doesn't make it green!
