As to the question about LR Cartos, from what I read on Vapor4Life's website, their Premium Cartos have a lower resistance to provide more vapor. I have used both the Premium and the regular and there is a noticeable difference in the vapor production.
As for the tornado, from a cost effectiveness perspective, if you are looking at it for the longer battery life without adding much size to what you carry around, then consider building a box mod. It is pretty cheap to build and pretty cheap to maintain. Including 2 14500 batteries and the charger I spent around $30 to build it. Should a battery ever croak on me, they cost about $5 to replace. Honestly the 14500 batteries will likely last longer than the Tornado ones as well given the higher mAh rating on the 14500s. On the other hand, if you are looking for simplicity, go with the tornado or a Joye/Janty Stick with 510 adapter as its prebuilt.
Just my $0.02