I spoke to Chiswick Honda, they say none of the modded bikes have come back to them.

Bike back from Honda Chiswick

not stalled on way home. Before ECU change stalled about once a day in traffic hard off throttle.

Honda advised entire bike needs fixing - £600 +! Local garage said rear tyre worn otherwise okay.

Ok, maybe I am lucky! I had the mod carried out some 1200 miles ago by Firstline motorcycles in Arnos Grove, North London.
It has not stalled once in that time, I find it more responsive with a smoother pick up and top speed is up by 2-3 mph. Only downside is that its now only doing about 68mpg whereas before the mod it was around 72mpg. However, I can live with that, as it is a brilliant scoot and still puts a smile on my face everytime I take it out.

update:

had my mod done a few months back, one stall.