Charger on my e-bike uses 122 to 127 watt, only just got it so still working out what it will do.
I have ridden my wife's and my e-bike, wife's mid motor, mine in back wheel, I found on the canal the locks are often twisty and steep so with no motor often easier to dismount and walk through the lock, however the hub motor reacts faster than the mid motor as no gears for motor drive, so likely the hub motor will work better at the locks to mid mounted motor.
However other that the locks not sure the motor will help? They are limited to 16 MPH and I find at 70 my speed is around 10 MPH so in your case likely it will mean ½ hour rather than 40 minutes, but also heavier, so any steps of stairs become more of a problem, and also more expensive which equals higher security risk.
With a £150 bike using a chain through the wheel likely good enough, with a £1500 bike, where can you put it safe? The second e-bike is folding so I can put it inside the car, not stuck on a bike rake outside. I use a bike to take photos, and with a non electric I can lift it over a gate and put where not in plain view tempting the theft, the electric is too heavy.
With roads in Wales the hill climbing ability of the electric makes it very worth while, but on the tow path not so sure it will help. Unless non legal type, the folding one has the option to set it for twist grip control, and yes tried it, but at over 16 MPH I can't pedal fast enough so it is basic all electric, and then battery does not last long, 6 miles no problem.
I did live in North Wales, and there were loads of reasonably flat cycle routes, either old railway routes, or following the cut, and with a legal e-bike which my wife has and my road bike I was faster than her, yes she would over take on slight rises, but I could pedal at 20 MPH, she could not, as gearing simply not high enough. Only after coming to mid Wales did I get an e-bike to help me up the hills.
An illegal 350 watt e-bike will likely do 18 to 20 MPH on the flat with no pedalling, with some raise and fall can get to 27 MPH, but the legal 16 MPH is not really going to help much on the flat, cycled along the river dee with wide cycle path with e-bike and it was not really giving any assistance unless wind in wrong direction.