Hi blather.
I haven't ridden any of the Innergy range but my advice would be not to bother unless you live next door to a Gazelle dealer who has been a Gazelle dealer for a long time.
Gazelle remain poorly represented in the UK for reasons best known to the company itself as their bikes are pretty decent quality machines. Kalkhoff, on the other hand, seem to be doing plenty of business in this country and are generally well regarded. Their prices seem to be climbing however and they may or may not offer the best value for money.
Much will depend on the topography of your local cycling terrain and typical journey length. If you are prepared to participate by pedalling with power off at times, rather than simply being carried along by sheer battery power, most modern ebikes have sufficient power to last through a daily commute into the 20-25 mile range. More with some of the newer high-power batteries.
Having a dealer close by who has been around for a while selling whatever bike you're interested in is very useful. Make a point of test-riding both a Panasonic powered bike like those you mentioned and a hub-motor type, of which there are plenty to choose from, some much cheaper than the Gazelle and Kalkhoff.
Regards,
Indalo