That is very different lighting than in the OP, which is far more contrasty. It is very flat. None of those three exposure readings should be expected to be much different, or to blow out the subject.

The underexposed ones ('500 and '1000) look underexposed to me.

The lighting is so flat that all of them could be called "acceptable" exposures except the last one ('1000 shutter speed), which is too dark to use without some manipulation.

The '500 shot looks much different than the '400 shot, which is odd, since the '250, '320, and '400 shots don't look all that different from each other.

My favorite is the '400, followed by the '320. I believe the '400 shot best represents a good density and renders the lighting ratio most accurately. '250 and '320 are too bright, and '500 and '1000 are too dark. But, as I mentioned, the very flat lighting does a lot to cover slop, so all but the '1000 shot are probably good enough to use.

I really suggest a more controlled test, done with artificial lighting and a tripod in various lighting ratios.