While not dosing straight vodka I have been dosing nopox then diy nopox (which is vodka, vinegar and rodi) for I dunno 5 years? Probably longer, maybe 7. Way back when I started it was to bring down no3/po4. Now it's just part of my daily routine that keeps my system stable. Obviously it is still helping keep nutrient levels low enough but at an even level not a reduction.
My experience is basically entirely anecdotal as these days I just periodically check the no3 / p04 levels and have not adjusted my dosing amount in years. Filter socks clog twice a week, skimmer is very dirty and cleaned out once a week. There have been no long term side effects. Corals are healthy as are fish. I should point out my bioload has not considerably changed in a long time and I roughly feed the same amount of food each week.