Drives are so cheap nowadays that the warranty is rendered almost meaningless.
Personally I'd go ahead and flash it to either Liggy & Dee's RPC1/Bitsetting version of latest official NEC 3550 firmware or their unofficial enhanced write strategy one.
If the instructions are followed correctly it's very unlikely to go wrong and even if it does go wrong it's unlikely to happen in a manner that can't be fixed
I suppose it depends on how much you value the warranty.
From my own perspective though I wouldn't want to put up with sub-standard performance just to retain a warranty when for a small risk you stand to gain enhanced useability for the entire lifespan of the drive.