I've never heard much as about inconsistency (its a pretty simple process, they'd have to really screw around to get major inconsistency but if its possible its possible in Russia).
Bootlegging is a HUGE problem however, and brands like ararat cognac are pirated massively, and have even had problems with bugs and things.
If I am out and see an attractive bottle (Gray Goose has a beautiful bottle), I will ask for that and so far have none of the problems that I had with Fleischmans, and other "bar rail" vodkas I had before.
As I said, I never knew when I would get the headaches, but they were crushing, so I assume it was from certain batches as opposed to brands, maybe some impurities that wouldn't be filtered out in cheap vodkas. Or who knows, maybe it was all in my head.
I would be interested in trying this new brand, because there is also a subtle taste difference in vodkas, I notice that the higher quality, the smoother the taste (not unlike many liquors).