It's probably a dissenting view, but I'm going to suggest "look to Europe." Most European countries have a 250w maximum and pedal assist only (no throttle rule) and Australia, where I live, follows this as well. My tourer/commuter has a front wheel kit because I wanted to preserve my "mullet" gearing at the rear (1x9, 11 to 46 teeth. I'm a weirdo, I know, it's microshift and I love it) If you're happy with whatever gearing fits, the rear wheel is better for traction, but I can still gravel climb with the front doing more than me and don't lose traction, even on a 2m 50%er I have to throw the bike at flatout at the bottom and nearly stopped at the top. (Might be a 30%er, we Aussies are given to beer talk, even when sober.)
Now, I know there are a lot of people here on EndlessSphere riding much higher power because the USA has been slower to restrict eBike power. This is good but also not so good. I mean a kilowatt will get people biking more, but I have a heart condition with a medical maximum BPM of 130, a 90 year old's MHR at 63 and 250w feels like me before before my NSTEMI (The "widowmaker" according to the local paramedic culture) That's at 20% pedal assist on the flat. Full power, all 250w, makes me feel like Cadel Evans on the Champs Elysee! Even with panniers on for a week away!
I live in Melbourne, Australia, and there are some nasty breath suckers between my place and the CBD. Short but nasty steep. These are the hills that I avoided before adding an e-kit to my beloved long hauler (not a surly, just what she's designed for, slow grinding the miles, well, kilometres here, but they look more impressive on paper
) I avoided these hills before my heart popped a big end.
Anyway, my nearly 2am AEDT sleepless point here is, don't fear a proper e-kit. My only regret, after resisting for years, was overestimating the battery I "needed." If you're just after a hill boost, you'll get that from 250W, you'll feel at least 20 years younger most of the time on 20% to 40% boost and you'll still get that healthy, aerobic workout without being so goddamned anaerobic on the big hills. 10Ah battery at 36v is more than enough for a commuter, probably a 7.5Ah is enough, depending on how big your hills are. There's no complication after install. Just a bike computer sized speedo and battery display, a small control box on the back of my seatpost and a motor in one of the wheels. My battery, though, yeah, 7.5Ah at 36v would have been way better than the 15 I bought. For around the city, anyway.
Wheel drivers are inefficient, can be noisy, are frankly not easier to install, looking at most of the designs and they slip badly if you get caught in the rain. They look attractive because they look like there's only one thing, not a collection of bits. If you're worried about the technicality of installing a wheel kit, talk to the bike shop that does your services, buy the kit they recommend, have them fit it. I used to work audio production, have a background in electronics AND have always serviced my own bikes. I found install a challenge, a physical one, too. But that lasts a moment, then you have a purpose built bike with an electric assist, that's as easy to use as the front gears on a 3xN derailleur setup... except you've got 5 or 6 of them, or off... easier, actually. button up, button down. Want to go? Push a pedal. Want to stop, grab the brakes. As easy as riding a bike, really.
The Europeans are killing it with eBike adoption, and pedal assist is why. It's still like riding a bicycle, just with a robot giving you a "backie" (or a "dink" as we call it in Australia)
And the other reason, as I mentioned above, I love my current drivetrain setup. It would be a bummer to alter it for some other configuration if I can simply utilize it with a boosting setup.
