IF, repeat IF, you melted the phase wires on the 1500 watt motor, that would indicate your hills are pretty steep and/or long. Hence my question about time to clear the hill. I did use the phrase "a minute or two" in reference to overheating times, on this type of motor, it would be more like 3-5 minutes. If you could describe the specific symptoms of the failure, then it will likely be possible to isolate the environmental factors that caused the failure.
Also if it failed while actually climbing a hill, or some other factor. Hall sensors can fail due to heat, however more often the component itself is just bad, or fell out of position, either due to severe vibration or shock, or just bad glue. The part itself is a few dollars, you need to open the motor, install new sensor, and solder a few wires. Putting the motor cover back on is a bit tricky, the magnets will powerfully yank the cover out of your hands and you need to make sure all fingertips are clear. There is a "KLANG" video which shows this quite convincingly.
Only by knowing how and why the failures occurred, can suggestions be made to avoid the problem in the future, on your next kit.
Beware the crank-drive salesmen. A fair number of people on the internet get paid, actual dollars, to push crank drives. Dealers who engage in such practices generally do not get a recommendation from me. For some dealers, this is only one aspect of their business practices and modes of operation, some of which are truly horrendous. Such dealers I categorize as people I would not do business with.
The crank drive has it's place, if you have severe hills and enjoy doing extra drivetrain maintenance and do not want to do the research to choose the proper hub motor for your situation, they might be a good choice. BUT, a properly chosen hub motor will do the job for less money and less hassle.
Also, with most hub motor failures, you can still pedal the bike home. If an overpowered crank drive breaks your chain, or snaps off a clear cluster, you are walking all the way.