[lincpimp]

Less weight is better, but you can use a lower mah battery when going to 5s and get the same runtime, so the battery weight should be almost the same.

There are most likely others here that have more experience with the neu motors than I do, but it appears that many use them on 4s in buggys and like them alot.

1515 seems to be overkill in a buggy, so the reduced weight should be fine. I would like to see someone use a 1509 turning about 50k rpm and geared for track usage. On 5s or 6s so a low kv motor would be required. I have some smaller motors that I will try in my hyper8 on 6s and see how they perform.