Leo I can't quite get the same flavor out of the lite/r91 clone as the 3.1 clone the draw is a lot stiffer even with the airflow screw removed , that could have something to do with it or I just haven't found the sweet spot as far as the build for this particular version , but the 3.1 clone is a lot easier to dial in , IMO , there's only about a 1/4 inch difference in size between the 2 , so I opted to get another 3.1 also found the threading on the 3.1 is better as well but YMMV .
The R91C has airflow deficiencies as compared to the 3.1, I did a measurement a few days ago and the 3.1 is alot bigger in dia than the 91...IIRC 1.7X bigger... I definately prefer the 3.1 to the R91C, the 3.1 has a richer taste and vape temp and density