Mine started the SECOND I went stage 2 in my Eddy, another chap posted the other day his went a day or 2 after going stage 1 in his Eddy. Luck (or lack of) of the draw, both R-Tech tuned. Some slip at stage 1, some don't at stage 2+. Depends how those 70k miles have been driven, maybe.
I have a custom linear map, that won't save your clutch, the extra ft lb torque will still be there at 3k-4k rpm when you put your foot down in the higher gears.
Personally I'd plan on needing a clutch when adding power to a manual car and if its not needed its £1k towards something else bright and shiny!