Very interesting, Chris! It is a real piece of luck that the modifier also changes the color in the intermediate stages.
I wish I knew of more indeterminate Beta OP's that are larger than Jaune Flammee. (Great tomato all the same, I was impressed with the earliness and production from the seed you sent me, thanks!). If you had some larger fruited that are already beta, it would save you a lot of space and time, since size is one of the hardest things to recover from crosses with small fruit.
I could send you seed of my F4 out of Zolotoe Serdtse, which is paste shape and size, but presumably Beta/- and sp+/- with whatever semideterminate genetics also in the mix, so still the linkage issue in play.
I would have expected the Beta - sp linkage to take a real beating in a cross of 97L97 and Jaune Flammee.
I mean, I thought it should segregate normally because of linkage to both sp+ and sp-.