Late to the party but I thought I'd throw out my experience. I've got a 1st gen x-Frame from the first year of production. I have run 300 gr. FTX's, 350 gr. XTP's, 350 gr. Sierra's, 385 gr. Remingtons and 400 gr. JFP Sierras. Probably about 1000 rounds since I got it. Not a lot to say other than mine reloads very easy. I don't size the cases all the way down, only about 2/3-3/4 of the way. The rest of the way just isn't necessary. Depending on the bullets, I don't always flare the mouth. Because most of the jacketed bullets I run have nice rounded edges on the base they run right into the case without having to do the flaring operation. I put a firm crimp on them and I crimp in a separate operation from seating. I recommend this method.
I've run H-110, Lilgun, H-4227, and AA9 through mine. Lilgun and AA9 are the ones I've used the most of. AA9 has been very accurate but does not run nearly as fast as Lilgun. Lilgun gives me both accuracy and top velocity but it's also given me some pressure problems here and there and I never had any problems with pressure with any loads using AA9, it just wont do that. That said, if you're not pushing it to the max, Lilgun should be fine. I was never impressed with H-110 in the 500. It's dirty as hell and didn't perform as well as the other powders.
As for primers, I've run CCI's, Remington 9.5's, and Winchester LR's. My mainspring is a little bit on the puny side so I had some trouble with misfires with the harder primers. With a little help from a friend at Sierra Bullets I finally settled on the Rem 9 1/2's. They've pretty much resolved the problem... pretty much. The one callout I have is that I was specifically told to avoid Federal primers because they tend to be the softest around, and in a big heavy recoiling rig like the 500 you want to make sure you don't end up with a chainfire situation due to recoil. I think the likelihood of such an occurence is probably nil, but still. Best to play it safe when you can.
Again, late to the party but I hope the info helps. <shrug>