Hi Bob
I have seen various recommendations made to you, ranging from Wispers to Kalkhoffs to Cytronex. All the usual suspects in fact
.
I would suggest that your first decision should be whether to go crank drive (panasonic, yamaha) or hub (Suzhou Bafang, Tonxgin). If you are a fit individual, you may not like the cadence restrictions that the crank design forces on you, however I think you will get more range and possibly better battery life overall.
If you don't like cadence restriction (and personally I hate it, and I'm a pretty fit rider) then you have to look at the hub designs.
I have both an Ezee (Suzhou Bafang) and a Cytronex (Tonxgin), and would make the following observations, given your intended commute.
The Ezee (which would be similar to the Wisper in many respects, throttle controlled, big battery, powerful motor) is a good bike, and with sufficient batteries could cope with the commute. It would certainly take the sting out of the hills. It could achieve a very high average speed. It would be easier than a normal bike. Much easier.
The downsides:
Cycling without power assistance is not much fun on these designs. It's possible, but they will in all probability feel far worse to you ythan your steel mountain bike. Like riding through treacle. This means that you will in all probability use some level of power assistance all the time, which in turn leads to -
Cost:
The big e-bikes (well mine anyway) go through ordinary consumables at a far greater rate than a normal bike. Think chains (needs two at a time when replacing) brake blocks/pads/discs, in my case the front pads are shot in no time at all brake/gear cables need to be for a tandem (at a greater cost) etc etc.
The biggest cost by far however is batteries. Batteries which get the sort of use that you are indicating will probably not last two years. They may do of course, but the range would be reducing significantly towards the end. If the end of the two year period was during cold weather the range shortening could be so significant, you might not actually make it. To be certain of getting the range required you would need two 14ah batteries. These currently cost over £500 each. Over a grand every two years? You could of course just buy one and recharge at work, but with two daily charges, it wouldn't take long for it's performance to fade. I reckon around a year if your lucky? That would be 480 charge cycles assuming 4 wks leave and no weekend use. In my experience these batteries start to decline around the 200 cycle mark? Remember also that the batteries take around 5 hrs to charge.
Therefore, I would urge you to try a Cytronex. Unfortunately Mark does not (as far as I know) offer the sort of test ride you need, however I do think that the Tonxgin system would suit you well, as it is primarily aimed at fitter cyclists who want a hand up the hills.
The bikes ride like normal bikes without the assistance, the battery and motor wheel are easily swapped out to give you a normal bike if required and the maintenance is no higher than an ordinary bike.
The Cytronex system uses nimh rather than lithium batteries. The batteries are around £200, will give you 20 miles on a charge and can be recharged in 90 minutes. Nimh doesn't suffer the same degradation as the lithium types, and I believe it is possible that you would get 18mths to 2yrs out of one, although other forum members would be able to advise better on this.
Anyway - just my opinion. I know that longer ranges than I have assumed have been quoted for the Wisper bikes, but on a commute I reckon if the power is there, you will in all probability use it!
Cheers
Nick