Taken the plunge.

[kwackers]

Whilst I'm here, as an update.

My conversion has done around 2000 miles now with no obvious problems other than a few self inflicted teething problems sorted in the first few hundred miles.

I never got around to sorting out motor cut offs on the brakes, I think they'd be an improvement but not much of one so I doubt I'll bother.
I find now I only use 2 or 3 gears on the rear (9 spd hub).

I charge the battery twice a day, once in work and again when home. I've never ran out but into serious headwinds the battery warning indicator has flashed although if I dropped the assist I suspect it would stop (it works by monitoring the battery voltage, I don't think it has a clue how much charge is actually in the battery).

I don't find the assist level to have that much effect on the battery mileage. Any affect is massively dwarfed by the effects of headwind. On a still day the battery claims to be between 1/3 and a 1/2 full after 20 odd miles. Into a headwind it indicates anything between empty and 1/4 and that doesn't seem to matter what assist I used. High assist uses more power but then it gets me there faster. Low assist uses less but takes longer.
I'm sure there actually must be a difference but compared to the wind its negligible.

If you put it on a very low assist and then drive it mainly from the pedals I'm sure it'll go much further, but I get the motor to help out most of the time and into an headwind who wouldn't want that?
I do feel guilty pedalling past cyclists having a really hard time into the wind though...

With regards the wind I do feel that this is one of the places mid drive really shines. I've cycled into 40+ mph headwinds and being able to drop a few gears so the motor has more available torque seems to help enormously rather than having the motor struggle below it's optimum rpm.

With regards the whole 'fitness' aspect. It still is only an assist, so you really need to be pedalling to get anywhere. In that respect the adage "it doesn't get easier you just get faster" applies in that it simply seems to make you feel fitter. In practice I pedal just as hard.
Plus nobody would ever claim that riding a tandem didn't up your fitness and basically that's what the motor amounts to.

Overall my main issues are probably with my choice of bike. Whilst it's a good bike I don't feel that a tourer makes a great electric bike.
The drops don't really make sense and I think given how you ride it a more upright position would be preferable.
There's little need for lots of gears so a 5 or 7 speed system would suffice (a hub would be brilliant) plus it gives you a slightly heavier chain. Fatter tyres and possibly a bit of suspension wouldn't go amiss and disc brakes should be a no brainer. Plus obviously some luggage capabilities...

I think at some point this year I'll find a suitable donor, move everything across and convert my trusty steed back to a tourer.