No experience specifically with Barred Rocks but with different dual purpose birds from hatcheries.
Tractor Supply chicks are from hatcheries, If you ask the person in charge of the chicks they should be able to tell you which one.
Tractor Supply used three different hatcheries last year, not sure which ones they will use this year.
Before the Cornish Cross were developed by selective breeding, certain breeds or strains of breeds were developed as meat birds, mainly Delaware, New Hampshire, and certain strains of White Rock. If you breed to enhance certain traits and know what you are doing you can enhance those traits. If you do not breed to enhance those traits they can be all over the board, pretty random. They will just be average, like all the other similar breeds. The breeds that were developed as meat birds have not been bred for meat properties since the middle of the 1900's when the Cornish Cross was developed. I just can't tell that much difference as far as meat birds go between the breeds developed for meat and other dual purpose breeds.
The original dual purpose breeds were developed to provide a family with eggs and occasional meat. This was before our obsession with huge birds. Mom could feed a family with five kids off of a single dual purpose hen. Some of the pieces on the platter were neck, back, and liver in addition to normal pieces and they normally had a lot of breading or were in stews and such so they could be stretched. She could cook them so they were delicious regardless of their age but many people today that are used to the chicken from the store or served in restaurants would not like their texture or possibly flavor. I don't know what would make a good meat bird for you but it is likely quite a bit different from what satisfied the people who were raising and eating the original dual purpose chickens.
One thing I've noticed with various breeds of hatchery birds is that you can get a wide difference in size with cockerels of the same breed from the same hatchery. When I want a new rooster to bring genetic diversity back into my flock I normally get 15 to 20 so I can keep the best. The last time I did that I brought in 18 Buff Rocks from Ideal. Some matured early, some matured later. Some were a lot smaller than others. Behaviors varied a lot too. I only got three that made it to the final cut. The rest were just unacceptable. I've seen the same thing in other dual purpose breeds.
If all you want is meat you cannot beat the efficiency of Cornish Cross, their feed to meat conversion rate is tops. The Pioneers or Rangers do really well too but are just a bit slower. But if you want a "heritage" breed, I don't think you will be able to tell that much difference in Rocks, Wyandottes, Delaware, Sussex, or Rhode Island Red or Whites.
If you want a heritage breed, my suggestion is to try some and see how they work out. Your goals and desires are going to be different from mine so what I like may bor be what you want. If you don't like them you can just eat them and try something else.