sharkbite flex hose

I am considering replacing my stuck water heater gate valve with a sharkbite ball valve/flex hose, but in my research I came across 2 instances of sharkbite flex hose deteriorating and showering rubber flecks downstream. I have seen both braided flex hose and corrugated flex hose from sharkbite. Looking into the corrugated flex hose I see metal, as if there is no liner to disintegrate. The braided hose is black inside. What is the difference in the 2 types of hose? Is corrugated newer so as to deal with braided liner issues? Is this a valid concern? I have seen no manufacturer response, and I would think they would be all over this.

Also, if you wouldn't mind, will a new gas water heater come with a preinstalled male nipple at the water line connection, or does it have a female threaded connection that won't work unless I buy my own double male nipple to install prior to connecting the 3/4" flex hose connector?

You will have to purchase a dielectric nipple set for the top of the new water heater.

Thanks for the reply. I still need advice from users about whether the flex water line with push-on quick connector has a problem with the liner deteriorating and showering debris downstream. Surely others have used such a product and can comment on its durability?

I would like to know if all gas water heaters require the purchase of a nipple to connect a flexible water line to the top of the heater. Maybe some provide the fitting and some don't? If I am sweating a copper line to and from the tank, does that mean that a sweatable fitting on one side and a threaded end on the other side is readily available? If the fitting's threaded end is male, then there would be no need for a preinstalled male fitting on the tank, but rather a female.

Water heaters already come with factory installed dielectric nipples
As for the flexible hoses I have used them before and I have not had anyone ever call me about the symptoms you were talking about. Granted I've only used them in a select few situations.
I have heard about the deterioration but I've never experienced it first-hand.

My code requires minimum 16" of copper off the top of a hot water heater. I can't see a reason why anyone would want to use anything else. Copper is tried, tested and true. I wish more people used it.