Good point ! Supposedly a tobacco variety will adapt to it's environment and within about 3 years time will be "different" than the original seed. I 've never really believed that and was planning to do the same thing with, believe it or not Havana 142 but since I've grown BSS-Maden for 4 years now I plan to do a comparison grow of it next year. I do believe that plants adapt to their micro climate but I do not think you will be able to distinguish sub varieties within a variety. I think soil type makes more of a difference than actual location.
Based on little expertise but gleaned knowledge I have the belief that saving seeds from plants acclimated to soil and climate may do better, as far as changing genetics is way over my paygrade
. I have noticed my MCB did better last year from a previous drought year. But a drought year can make for a bad comparison. This year will be the third generation from original seed obtained from europe of which had a crummy germinater[No no no it wasn't me
] and germination rate..
An example that may or may not prove out is Guatemalen. I had an unusual problem with sunburning on well established mature but not ripe plants last year. Huehuetenango also but not so bad. After a bit of learning, Not much out there I discovered Guatemalen can be considered a wrapper, derived from a burley variety
[correct me if i'm wrong, this is from a fading memory of gleaned info., no recources as of yet to substansiate, till I backtrack them. ]
I know it is a wonderful filler with a mild flavor as is the MCB. I will try some in shade this year and a couple in full sun, just because they have proved difficult to harden off also.