Definitely not. I absolutely never recommend anyone flash the BIOS on a graphics card unless they are having severe issues that cannot be resolved via any other means at all.
Graphics cards are extremely touchy about BIOS flashes and I've seen many many cards end up dead from what is in theory a simple BIOS flash.
Unless you are having severe issues with operability that Gainward has advised you cannot be otherwise fixed unless you flash the BIOS then I would not even consider it.
Graphics card BIOS flashes have always been a much more tenuous area then flashing the BIOS on a motherboard, and is not to be taken lightly.