Just a few thoughts for you:
1. I assume you know you can adjust the seat post stiffness inside the seat tube right? It takes an allen key. Thread counter clockwise to soften it up.
2. For the headlight, you can upgrade. The one that comes on the RX Pro is significantly better. 3rd party options are better still. I bought one similar to this to supplement (2 beam model), and it works quite well on my RX for very cheap. No internal battery, just powers off the bike battery, and gives a nice wider spread to illuminate the trails edges.
https://www.lightinthebox.com/en/p/...g-caving-everyday_p6563348.html?prm=1.3.55.11
3. The hub drive is unaffected by the gear. Selecting a "matching" gear for your speed only serves to allow you to keep pace if you want, or use the PAS to maintain your speed once you get to your target. It is nice to be in the right gear to apply a little leg power instantly if you need it for a hill, or want to back off the throttle for a bit.
4. If you ride throttle only, just be aware that if you drop too low in speed with a high assist setting or throttle input (like on a steep hill), you can overheat the hub in a couple of short minutes. Can do damage if you do it repeatedly. Just something to keep in mind, and teach the kids so they don't fry your hub. The overtemp cutoff in the RX works well (I can tell you from experience), but the resistance once it faults out makes the bike very hard to pedal until it cools down.
5. I'm 6' and also plan to adapt the bars in time. Same issues, which I have partially rectified with bar ends for variable grip positions, but ultimately new bars will provide a better fit.
6. I found all the bolts needed re-tightening up to the first 1000km. My RX was factory assembled in Van, and I had loose creaky cranks at 200km, lost a fender nut at 300km, and just did a full overhaul at 1000km, and found a number of additional loose ones. Any that come loose again will get some locktite.
7. The Rize stock chargers seem marginal. I have 2 rize bikes and one charger melted on the first use (fan didn't work - they replaced it within 3 days). I also find the charge level is slightly inconsistent. I'm ordering a Grin Satiator for the house, and will relegate the stock chargers to occasional travel use.