I have Orange Essence topworked on to one of my trees (NDM #4). Got a fruit last year (delicious) and have about 15 on the tree this year. I have Taralay also grafted on the tree and that part of the tree produces a lot more than the OE. But taste wise, it doesn't even come close to the OE.
From what i have seen on my tree, it doesn't flower heavily but holds on to fruit. I have had it for about 4 years and this is the second year fruiting. I have a feeling it will become more productive with time.