That is be cause you are using a super smooth plastic beater. Try a felt or rubber on a Remo costed head and the coating on the neater area will wear...
Try Bosphorus, Turkish, Mehmet/Agop Istanbul as these cymbals are actually handmade in Turkey. I have owned many Bosphorus Traditionals and can tell...
Not sure about Roland e kits. But my new DTX500 makes some slight background hum when the volume on the module is turned past ~70%. I am using a pair...