I have never ridden a hub drive so I can't give a comparsion. I have a Bosch mid-drive with the Active Line Plus engine, nominally 50Nm. The (presumably maximum if the engine is trque-limited) torque addition levels are +40%, +100%, +180%, +270% for Eco, Tour, Sport and Turbo modes respectively.
For the OP's understanding I will give a little possibly tedious detail of my heart condition. I'm 67 and have dilated cardiomyopathy diagnosed 3 years ago. I have always liked bikes and always had them, but have never been any good at hills. Now I know why. My ejection fraction in early 2018 was 19% and I got breathless crossing the road. No question of cycling then. Now I am back to 55% or so and feeling better than I did before I knew I was ill, but beta blockers take a lot of the force out of my contractions and help limit my heart rate to about 120 unless I overdo it. My cardiomyopathy no longer stops me doing anything, but I simply don't produce enough power to climb proper hills unassisted other than with a struggle in the lowest gear, at sub-walking pace. This takes the fun out of cycling,and leaves me exhausted after only a few miles.
John if you are up to it, the torque-addition approach could work well. I need cardio exercise, what I don't want is a heart rate of 130 or more which would be dangerous. The point NealH is sensibly making is that, because the Bosch augments the rider's effort by a notional percentage, it can only assist if you are making an effort in the first place. The critical question is whether you can make sufficient effort do your share of the total amount of work needed to get up the hill. NealH has also made the point that a cadence sensor only bike that only requires you to turn the pedals might be more able to 'rescue' you if you were simply unable to put any real effort in.
I ride the Bosch in Eco for the most part, which includes gentle gradients or into a breeze - but probably not both at the same time. My ability is such that I can do this quite well, without a struggle and without my heart rate going through 120. Some hills I can get up in Tour, but if I need more assistance I'll use Sport or occasionally Turbo. The lowest gear I have used so far is 3/9 which is 41" on my Cube so I feel I have a bit in reserve.
My daughter also has mild dilated cardiomyopathy but has had more difficulty keeping her heart rate down, on a lower dose of beta blocker, than I do. She cycles a lot, and has a Shimano Steps E5000 mid drive (40Nm) city bike and a cargo e-bike with a Shimano E8000 engine (85Nm). She normally uses maximum support (the Shimanos have 3 levels) although she is a stronger cyclist than I am, just to control her heart rate - she is in Cambridge where there aren't many lumps but she usually has a 4 year old and a 6 year old on the back of the cargo bike! The cargo bike takes off like a rocket in Level 3, but pretty lively even in level 1 and I suspect it is actually programmed to give an extra shove for starting off.
My tip for the Bosch drive or similar is to use the gears as you would unassisted, to keep your cadence up. Bosch advises that 50 or more is optimal, and around 60 is comfortable for me if the effort isn't too great. By doing this you will get more power from the bike, assuming it is torque limited to the stated figure. At first, instinct sometimes caused me to increase the assistance before changing gear, but I soon worked out that I needed to use gears to get the the best out of the drive, just as I do with human effort. Because the motor is acting through the chain, use of gears can maintain its RPM and thereby avoid a power drop at low speeds.
A Performance or CX engine (in the Bosch range) would of course give you a higher reserve but the ALP seems fine for me.
I've found my Bosch, and my daughter's Shimanos when I tested them, both to be very natural to ride. I don't expect the hub drive to feel as natural when I get the Swytch kit for my Brommie. Quite how much that matters I don't know - lots of people with more e-bike experience than I seem quite happy with hub drives but I can't speak to that.
I am super-happy to be able to cycle much more pleasurably than I have done for years. So far, by keeping my pedalling speed up and using the available assistance I haven't ever felt I was struggling, and I do feel I am getting useful exercise.
John Gray, feel free to PM me if you have any questions.
