I personally don't consider cards like this part of the master set. They're more like trophies rewarded to certain individuals.. I know some people do but I don't know, I don't think they should be included in the master set. There isn't enough of them printed for everyone to obtain.
True, but there are cards with unique arts with only 100 or less copies that everyone counts, so I don't consider this an exception. There will always be holes in my collection, but imo a master set has to include every variation regardless of my emotions behind it. You can however limit a master set to whatever you want though, as a collection shouldn't be about having everything, but the journey of collecting. Even the richest people in the world will never be satisfied.