When I quit a multiplayer game in BF3, the game warns that "All progress will be lost". But I'm wondering if experience and unlocks will also be lost.
The ONLY things that you lose for ending a game early are:
Any points/kills/captures etc that you would have received while continuing to play.
The ribbon for whatever gamemode you're playing (including the winners ribbon).
Any end of round only ribbons like MVP or Ace Squad.
It will always count as a loss on your record.
You won't lose any progress that you made during the match, including ribbons, medals or service stars.