Your correct the WW controller is for range and smoothness but still packs a punch if you want it. My buddy has the 2300w version and it scares him so he only rides in ECO mode, waste if you ask me. I have the 1500w version and always run in sport mode usually level 2 90% of the time.
I have 4 friends that have either the stock Bafang M620's or a Biktrix M620 and after we adjusted the programming they like them just fine.
Nice to have the UART connections. Just buy a stock motor ( if you can find one with the UART protocol ) and tune it yourself you'll never know the difference.