Get a MB-20 handle for it, transforming the body from a F4S into a F4 vanilla. Only 4 batteries, same ergonomics, a *lot* lighter
I had an F4 with both grips for a while, and I will caution you to make sure that you use very fresh batteries when you are running the MB-20 handle. In fact, I would only run it with lithiums, myself. The camera was dead realiable as long as it was getting enough voltage, and "enough" for the F4 is apparently more than for my other nikon cameras. I have a theory that Nikon stopped selling the F4 without the MB-21 battery pack because the 4-cell handle was causing them reliability problems.