Totally closed except for that 900ppm of o2 left in a sanipurged keg. Sorry I had to be that guy. On the bright side.. It's better then the other way!
Dude, I use your purging method. Got a better one?
I know, its better! but its not perfect. The fermentation purge is probably your best bet, but even there I still cringe at the thought of transferring finished beer.
The "pros" can put a sankey keg though the same cycles as a bottle with a dual/triple purge/vac. Then can discard the first runnings/keg and not flinch. We don't have those luxuries, we usually have one keg that we can't put though those cycles and 5/10 gallons specifically allotted.