Not knocking as it's a sound investment, but I've never seen the point in collectors paying extra for proof Krugerrands.I add 4 to the collection every year. I have at least 4 (have bought extra proofs when I have "good years") from every year all the way back to the year of my birth, which just so happens to be the same as the Krugerrand. I "spend" the proofs when I have bad years.
It's still going to be an ounce of gold even if it has been in a bag with other coins.
On the other hand, collectors generally are a weird bunch and will pay vast sums for anything they regard as special.