I have a friend who is one of the more experienced big bore shooters in the country, I think he's gone through ~twenty 454's, and 5 five 500's. I've shot a few 500's, and they really aren't any worse then the 475, shot a few of those as well.
I think there is also a misconception about the penetration issue. The 50 does penetrate slightly less then the 475, but only slightly. If I get full penetration with the 500, for a given weight of bullet, what benefit is their in going to a smaller diameter? I have yet to hear of any condeming the 500 as lacking penetration on game.
The only real drawback to the 500 is it isn't a factory round as the 475/480 is. The other issue is there used to be a shortage of parent brass, and that is what caused the creation of the 475. If more folks had used the 500 in the fields, there just might not have been jump to the 475. BBA makes outstanding brass for the 500, and CH4D good dies, so it's a straight forward project.
No, its Dennis, who posts as HHI 812. He doesn't post as much as Monte, and is the most rabid gun trader I know.
Monte is an interesting guy though, and I've shot his 475 and 500, the little 500 is a hoot.