I think with the little rise of Mono Red Chalice in Legacy, Ur Delver will become slightly a better Delver deck or a better choice compared to the other Delver builds. Since Blood Moon effects do not bother us the big challenge against it is CotV and Trinisphere while other Delver decks have to fight through all of it. I allready played against Mono Red Prison and it always came down to me finding hate cards or not. The matchup is very even though.