Thanks again to all who have provided valuable advice and input. It does appear that the Integrale is a bit of a risk with the high cost and issues with the motor being enough to make me rethink.
I like the look of the Giant Quick E+ which appears to be the same design ethos as the Integrale with perhaps less of the risk.
I understand that the Quick E+ is not available at them moment (or a least showing out of stock on the Giant website).
That it has solid forks would also probably help in the speed stakes.
Any other models/manufacturers that should be considered?
Many thanks,