Pandan,thank you for the link. Now I know what a Bumper satsuma is.
Boris, I have never heard of any of Moy's citrus research/development work and varieties. He and his team did some great work on developing these cold hardy satsumas. The Bumper sounds like a winner.
I have this unknown (had the tree too long from my dad without asking the variety name) but it gets a large cluster of fruits, reminds me a grapes. Check out the photo below. Have 2 of these trees and we get about 500 ripe fruits from the trees every year, all seedless.