Well, when you're talking about disease resistance qualities in heirlooms/OPs, you've got to consider that that view is generally coming from a commercial perspective. Tomatoes for market have to be reliable enough to be grown in large fields and they don't want the whole crop getting wiped out. They're pretty much all hybrids, so they've got that whole hybrid vigor thing going on. Flavor is also often traded off for uniformity of size, ability to ship long distances, quicker and shorter window of ripening time, etc. Many of your heirlooms will be late season DTM or ripen a couple here or there over a long period of time. That's a good thing in the home garden, not so good for market (or if you really want to can up all of your tomato sauce all in one day.)
If you're growing heirlooms in your own garden and taking proper care of them, mulching (really big deal...you don't want rainwater splashing back up on the leaves and transmitting soil-borne disease), patrolling for bugs, good healthy soil, etc. you are not going to have too much trouble or losses from disease. Every time I've gotten blight, it has been my own fault for not mulching promptly.
My favorite heirlooms/OPs are Black Krim (awesome flavor, pretty tomato), Delicious (huge beefsteak slicers with wonderful flavor), Black Plum (unusually deep flavored 2oz saladette, big yields), Kellogg's Breakfast (yummy, sweet, mild flavor and huge, great for showing off

), WV63 (good flavor, good for canning or slicing, and this one actually does have great disease resistance qualities), Golden Egg (cute little yellow grape tomato, tasty), Golden Jubilee (mild and sweet, my hubby's favorite tomato) and San Marzano (tasty and good for roasting/cooking).
I've got 23 OP tomato varieties in my collection right now and I've not even barely begun to sample what's out there, so I can't really say that I won't have new favorites next year.

I'm lucky to have a nice, long growing season here, so I'm not limited in what I can grow. I'm not looking to turn a profit on my garden, so big yields aren't an issue for me. I actually appreciate that they don't all ripen at once. I keep the canner going all summer anyway. I'm more concerned about how it TASTES and of course, it doesn't hurt if it is also
pretty!

I've grown a lot of popular hybrids in the past before I got into heirloom/OP tomatoes, but I don't grow them anymore primarily because I want to be able to save seed from my tomatoes and I really do think the heirlooms taste better.