We've had a few OKB rot, but they aren't particularly worse than any of the other varieties. It's just been a bad year as far as weather is concerned. But some of the blame is on me, for not fertilizing enough. I should say the rot I'm talking about is really sun scalding because of loss of foliage due to disease. We also have seen quite a bit if blossom end rot, which can be because of inconsistent rain, and/or calcium deficiency. The frequent rain causes fruit to split as well.
But as far productivity and disease go, the OKB are very vigorous plants, I had to stake them a lot, with a lot of branches. Their fruit production seems pretty good considering their size. Disease resistance looks to be better than most other types. The fruit above is about 13oz, which probably about average for OKB.
As far as other varieties that have resisted on the vine rot, blossom end rot, and been relatively productive are the smaller varieties like Chocolate Cherry, Yellow Pear, Mischka, De Barao, Mr Bruno, Jaune Flamme and Cream Sausage. Yellow Pear plants, though were among the first to get diseased.
The Pink and Yellow Brandywine's have been healthy, vigorous plants, and the fruit haven't shown any rot either. They've just been very shy bearers. I have a Black BW, which is a regular leaf BW, that's very productive, but disease hit it hard, so its fruit has been rotting bad. Seems like a lot of my purple/black fruit has been showing rot. Best tasting dark tom so far has been Paul Robeson, but still waiting on Black Krim and Trifele to ripen.
I brought in some Great White fruit yesterday, I'll try to get some pics and taste review when they ripen a bit more. They have yellowish skin when ripe. My wife cut up a properly ripe Pink BW, and she loved it, but it just didn't do much for me. Kinda sweet, but not much tang, and a somewhat unpleasant aftertaste. Very meaty flesh, not watery, or seedy.