When I grew Smyrna #9 (an Izmir variety) with wide spacing, it reached well over 7 feet in height, and the leaves were averaging about 12 inches in length, as I recall. It's resemblance to Sumatra types (FL Sumatra, Timor, Besuki, etc.) is striking: columnar form, vein angles, stem angle, leaf margins and surface, etc. There is no question that all Nicotiana tabacum varieties are genetically related, and that they have been differentiated over the past 500 years by the regional preferences of the growers, and their selection of desired traits.
As for the contract growers for GRIN, their classifications appear to have been haphazard, at best.
Bob