For what it's worth, I can't think of a single person who's had any trouble with their save game memory on an NEC system, off the top of my head. I certainly never have.
If you're really worried about it, what I would do is just get a Tennokoe Bank memory card and backup your system's memory every couple days and just forget about it. I really wouldn't be concerned until your system actually stops retaining it's memory. It's probably more trouble than it's worth to try and fix something that isn't broken yet, and may never be as long as you own the console.