Any of the newest motors seem to have plenty of power - the deciding factor for me is noise and durability of the gears/bearings. I currently own a Bosch CX4 food processor and an EP8 coffee machine (regreasing helps for a while but the grease disperses).
I think there will be better deals on superseded models over the next few months. The last bike I bought was a '22 Rise at 40% off new - keep an eye out for deals.
Why would anyone want to have only one bike :)
Keep it as a spare for when the Amflow is out of action or for when you need to leave your bike in a less safe place.
There are places online that sell bearings for the CX4 motor: BOSCH Performance Line CX (Gen 4) | eBike Motor Repair
You should also be able to get individual bearings from a local bearing supplier.
Probably won't know the exact cause of the problem until after-market repairers are fixing the motor out of warranty. The internal electronics are tiny in comparison to Bosch, so possibly something in the first gen motor isn't quite robust enough:
I fitted larger mudflaps to the rear of my car which stops a lot of dirt and spray from wet roads getting on the bike.
Most newer cars have small mud spats rather than a full mud flap.
I also carry a full bike cover in the car to use in heavy rain.
There's a repair guy for Shimano motors in the USA now, Grant Gunderson from PNW Suspension Service. He's on Facebook too.
https://pnwsuspensionservice.com/
I've spent a lot of time reading posts and looking at videos of EP8 disassembly and it seems that the 'traps' inside the motor are mostly rumor. As a novice mechanic I was prepared for the possibility of ruining the motor but by going slowly the risk is minimized. I'm always cautious of static...
My EP8 became noticeably noisier approaching 2000km so I opened it up (after watching a few videos) and after having previously opened a Bosch CX4.
There was no water ingress and almost no grease, especially on the plastic gear that runs against the armature shaft gear. There were green shavings...
I hope to own an Avinox powered bike in future for it's power to get up the steepest pinches, but I don't see any point in increasing power/weight from where they're at now. I'd rather see how light they could make a motor with a bit less power than the current Avinox.
I think speed restriction...
I've heard that the ep801 can't be opened without knowing the proper procedure - apparently Shimano added a trick to brick the motor for unwary home mechanics.
Thanks for posting about your problem - others can inspect their frames to look for cracks. Assuming it is a problem with the frame design it should start appearing on some other Amflows, whereupon you could revisit the warranty request. Otherwise you'll just need to put the bad experience...
Water enters the motor through the crankshaft seals; provided you don't ride through deep water or point a hose directly at the cranks you should be fine.