Here's the deal: i want to do almost all of my own work. But, I am getting older and can't climb hills like I used to. I would like an e-bike that will get me up a hill at 5 MPH, hey even 3 or 4 MPH would work for me. But, if I want to go faster than that, I have to do the pedaling.
My use case seems tb similar to yours except that I can't ride a bike and have to use a trike.
I am about 195# and the trike is another hundred. If I can make it to July, I will be 81 years old.. and not in particularly good health.
My experience over the past year is that an extra 350 watts will get me and the trike up any hill in the area at 3 mph - that's with me pedaling reasonably hard, but not killing myself.
My steepest hill is about 8 degrees at it's steepest and 1.5 miles long. 8 degrees is *really< steep... Not San Francisco steep, but a normal, healthy, fit person will be breathing hard just walking up it.
I have a geared hub and my lowest gear is something ridiculous like less than 26 inches. In my highest gear, I start getting spun out over about 18 mph. Spun out for me is somewhere in the high eighties cadence-wise.
Generally, hardware-wise, we're talking "Pedelec" mid-drive - where the motor is mounted on the bike's bottom bracket and there is a sensor behind the crank arms that can feel how much I am putting out and a controller in the motor that adds to my effort - more, less, or nothing depending on what assistance level I select by pushing a button on the handle bars.
Specifically, I am using a Tongsheng 52v "TSDZ2" motor and a 14 ah battery. The motor is rated for up to 750 watts, but I have it capped at 400. The way I use it, that combination has 30-45 miles on it with the battery never charged more than 80% or drained to less than 20%. Motor + battery came to a little less than a grand. They can be easily installed on just about any bike in about an hour if one knows what they are doing.
I dial up some assist whenever I find myself grinding up a hill or into a headwind. The rest of the time I ride with zero assist.
There's more....Reliable sources aftermarket firmware... Gearing considerations...Ping me if you are interested and I will tell what I know...