should I run a bw scanner authority?
Most likely not. Running a bw authority makes only sense if the results are also used by a dir auth, so unless your best friend is a dir auth operator you would first have to find a dir auth op that trusts your results. The bw scanner system is currently also being replaced by a new scanner software (sbws).
If you have spare bw, you can run more tor relays, that is always appreciated and does not require a trust relationship with a dir auth operator.
thanks for helping the tor network! nusenu