a few other notes on avocadoes... I find the browning is more of an issue if they are not at the proper stage of ripeness. Underripe also seems to mean they're more vulnerable to browning.
I understand that most avocadoes are picked when not ripe, they ripen off the tree. So I find the best way to go with avocadoes is to buy them moderately underripe, then ripen them at your facility. That way they don't have dents and squishes from some being overripe, they don't suffer issues in transit, and you can assure the proper ripeness yourself. If you need to speed up ripening, you can bag them with apples or bananas which give off ethylene which will speed the ripening. Overripe or older apples work especially well.
I would say try undiluted lime if yours are problematic, then drain well. I have also used undiluted rice vinegar which is farily mild, especially when making sushi.
But you might find them a little less prone to browning if they're at the proper stage of ripeness also, not over not under.
I've never tried the IQF but they sound very handy!