I've got a .204 Ruger in a Kimber 84 Varmint.....As my username may suggest. In fact, when my dad ordered it from the distributor, they told him that Kimber told them it was the first one out of the door. I bought it way back as a college graduation gift for myself. I love the gun and the caliber - problem is the coyotes moved in when this happened and they kill all the ground hogs, so I don't' shoot it much any more and my family schedule isn't conducive to hunting 'yotes at night.
The .204R has a lot going for it, but honestly, I don't prefer the smaller calibers anymore.
If I was to buy a .20cal today it would come down to volume of shooting. If you're just shooting it a dozen times a week at varmints in the spot light, I'd go with the .204R and find a factory ammo that it likes and not bother with loading. If you're planning to burn out the barrel in an afternoon of prairie dog shooting then I'd get the .20 Practical for the cheap and easy to find brass.
Good luck!