Got my 510 FLuXOMIXERS (stainless steel) today and I am SOLD. I did remove the atty cup first thing though (I suggest this for all). Only issues I've seen are don't overfill and right after the fill if you lay it on it's side some juice will seep into the atty and give you a mouth full of juice. This is probably because the atty cup is out... you be the judge.
Otherwise, good cartos all around. filling is simpler and cleaner with the pipet no more condom filling. Although they could consider replacing the sealing ring with a rubber tip that doubles as the seal. That way you just pull the tip and fill, no fiddling with paper clips to get the sealer ring out. I got a cool tip with my order that replaces the white plug, a modified longer version would work well in sealing around the atty.
I you don't have an ego PT, get one, they are the bomb, and $20 is one of the best prices I've seen. I'm thinking getting one as backup.
Vape on.