Alright. Now that I have a ready made ebike with rear geared hub motor, throttle, and cadence PAS, and a few days of riding done, I have something to add.
Before, I was going to build a stealth bike, but uncertainty stalled me out - I had never ridden an ebike. Simplification was very important...I didn't want to get stuck with a crank problem or whatever, during the build, and fewer parts and wires and connectors means simpler for my first ebike. I got a store-bought non-stealthy bike. My biggest concern is theft, now, but I'm dealing with that properly.
So on with the throttle and PAS.
I like the cadence PAS very much after picking up some techniques for shifting gears, changing PAS levels and pedalling, all in a mix. I don't use the throttle much but it is very important for being able to hit that to get the fastest full boost when necessary, for example doing a left turn off a multi-lane road. That is handy because not only does it get the job done in timely fashion, I also haven't altered my settings or gears.
So that is for city riding. For long haul like on a highway trip I'd probably want to mod the throttle to keep it where I want it most of the time.