Not sure about the EX500 MC but I wanted to provide my honest opinion on the ZRX1200 after about 100 miles of use. Holy cow what a difference it has made, the brakes are more responsive, the lever adjustment is extremely helpful and better than the 14mm bore of the Amazon MC, I don’t have to pull the lever halfway to get a decent stop out of them. If anyone is ever considering picking one up I would definitely recommend it!
I just looked at the Amazon listing for my old MC and it has a 14 mm bore, it I definitely prefer the increased braking ability of the 17mm bore from the ZRX1200 Master cylinder.