IMO, 50 feet is fine...if, and only if, you can accurately place a fly where you want it at 50 feet with a minimum of backcasting. I've fished the flats considerably for Bonefish, Permit, and small Tarpon and accuracy is very important...being able to hit a spot at 50 feet with only one backcast will get you plenty of flats action. Accuracy and minimum backcasting...that's the ticket.