I think you are right. I seem to recall reading a review of the HO BLI T1 that mentioned that the blind drivers have treads cut at a slight 3 degree angle so that when they hang inside a rail on a curve, they can get themselves back up over the inner edge of the rail without getting "caught".
But I would still prefer they not be blind. Blind drivers look funny on an engine that wasn't supposed to have them.
The Key T1 had a slight sliding/pivot connection between the two engine trucks which helped it on curves. On 18" and broader curves, I really didn't notice that they were pivoting unless I really looked for it. Even then, it didn't bother me.
On that kitbash T1 I made years and years ago, I just increased the lateral play in the drivers enough to let it negotiate 18" curves while keeping all the flanges and keeping a solid (non-articulated) frame. So it is definitely possible. But BLI may want to make this thing run on 12" curves to appeal to the broadest customer base.
