Thanks for the prompt, you are right it has been a while since this topic was last updated.
I eventually purchased an Accelerator Module from Marc at www.sol2.be
for my 2016 mk3 650.
It was substantially cheaper (£58) than the Boosterplug but on the other hand Marc is not quick, rarely communicates and doesn't send any instructions. This isn't his main occupation I believe. However he did eventually email me with a price and the module arrived within a week or so and if you look at Youtube you can find instructions on how to fit the Boosterplug which is very similar. Fitting was relatively simple.
The module was fitted in early May 2018 and I have covered over 3000 miles since and can say that the module does what I hoped and has improved throttle response at lower engine speeds which makes stop start driving around town much easier and far more pleasant. Fuel consumption hasn't been noticeably affected and is still averaging 70 mpg (although this is mostly slower non motorway speeds).
Marcs website explains what his modules do, although he doesn't show Kawasaki Versys as models he covers. Some memebers on here have not had a good experience, but apart from the above reservations I did not have a problem.
I hope this is of some help.