Of course, Big Beef is not an heirloom and is about as perfectly round as a tomato can be.
I often cannot allow my tomatoes, including my Big Beefs, to ripen on the vines. Quail population is an important factor in my garden. And, there are other
things.
I'd like to think that the supermarket labels are honest but, first of all, many varieties are now available that have only the
appearance of being an heirloom. Also, I was witness to a rather uncomfortable conversation between the president of a organic organization and a local grower who made no pretense that his produce was organic. However, one of the supermarkets that sold his produce labeled it as such. That was dishonest labelling and may have been a case of people not following due diligence.
Some heirlooms have their place in my kitchen and tomato patch. I'm happy to have them. This isn't a very tomato-friendly climate for varieties requiring a long season. I get by with some look-alikes

. Brandywine OTV is one of those. The cross that produced it occurred a few decades ago but it can ripen fairly well and it's productive.
Tomatoes probably cross a little easier than what most people would like to admit. That can make saving seeds a problem. Twice, I have been sent seeds that were supposed to be one variety but the fruit didn't fit the descriptions! In one case, the other qualities fit well into our garden and diets.
KayJay, my wife also likes mild flavored tomatoes. Thirty years ago, I don't know that I had ever eaten a pink or yellow tomato. My experience has been that they tend to be more mild than many of the reds. One of those packets of saved seed that was sent to me was supposed to be a big yellow heirloom. It was little and red! I thought, "Hey, this is a pretty nice little tomato!" Healthy, productive little plants ... I grew and saved seed about 4 times. Then! I had a plant with fruit that recessive yellow color. The other qualities were still there but the intensity of the flavor dropped. It's one of DW's favorites

. Save seed from what you like and if you have enough room in the garden, and even if you aren't into all the details, tomatoes can be lots of fun.
Steve
where do we think these heirlooms came from in the first place
?