tobeco makes a r91% clone, however, its not a 1:1 clone of the russian 91%...the airflow hole that gives the russian 91 better airflow (the bigger hole) on the tobeco clone, the big hole is actually the airflow control hole...so basically not really different airflow wise than the ehpro kfl+ clone.
between the ehpro and tobeco clone, i prefer the ehpro clone-performance is about on par with the tobeco clone, but seems to have noticeably better quality control. (currently my tobeco clone has been delegated to a dripper to test juices, my ehpro was 'stolen' by my roommate, and im rotating kfl+ v2 and my russian 91% between flavors).
that being said, as far as your concern about leaking, i've had no leaking issues with any of them (upside down, sideways, etc), though i wouldnt recommend a full clear tank section-i have a full clear tank/top section that likes to seperate from being knocked over on my desk. no issues with the standard 3 section tank, and no issues with the clear tank on a metal top piece, just something to note that i've found in my own experience.
the only time you may get some leaking that i've observed is if you pull too hard (assuming everything else is set up correctly) since that will cause your inner tank section to fill up with juice, and when tipped upside down, the excess juice may leak out of the drip tip. there is a cue that is occuring when you start getting gurgling.
/edit-the included drip tips have a tiny draw hole, so that actually also helps retain juice from leaking out, but also makes for a tighter draw
interesting side note-the russian 91% seems to have a secondary 'juice catcher' in the drip tip area-the screw in tip as well as the 510 adapter piece it comes with dont sit flush with the top and leaves a small gap that seems to further prevent leaking from chimney section by collecting juice. one caveat however is that it also likes to spit juice if there is excess in that well area and needs to be drained/wiped off.)
almost forgot to mention-there is a slight...i wouldnt say leaking issue, but with the kfl+ and ehpro clone, the fill screw is recessed and has an oring on it, whereas the russian and tobeco dont. this means sometimes u will find moisture on the bottom of the russian/tobeco when you take it off the pv...not that much or enough to cause any type of leaks that i've found but may be of interest to you.
for draw ratings, i would rate it as:
1.)russian 91%
2.)kfl+ v2
3.)ehpro clone
4.)tobeco clone
between the ehpro and tobeco though, its not really noticeable.
