Uhmm... Selection from primitive varietals necessarily means that the grower (breeder) tries to enhance one or more phenotypic trait that he (she) thinks is desirable or worth the effort. In doing this, other traits are necessarily lost. You may want to select for bigger leaves, or less suckers, or early maturity or even flower colour BUT very likely you will loose something on the way. Primitive strains are often (but not always) less productive, with pronounced suckering, less uniformity in size and higher in nicotine content. Nei their necessarily better nor worse than heirloom strains. Modern day hybrids are a whole lot different.
Primitive are fascinating, but it is my opinion that If they were so good, no one would have Made a selection for desirable traits in the past...
Pier