With regards to the frame breaking, thats not going to happen if it hasnt already. We took our trikes to Burningman and rode about 300 miles on very bumpy desert terrain while towing a small trailer and my girl standing on the back.
The reason I went with electric vs gas. We live in San Diego and they are classified as bicycles. We ride on the beach at low tide for miles, we ride on the boardwalk in Pacific and Mission beach, we bar hop down town San Diego without the cops hassling us. Its just more simple and we've never run out of battery yet. On this smaller trike I mounted the battery under the rear platform so its kind of stealth however in California there's no real need to be stealth.
Here are some images of my kind of matching smaller etrike.
Torker Trike
750W motor
36V - 10am hour battery
Top Speed - 25mph on flat
Distance 12-15 miles no peddling on flat