It doesn't affect equilibrium at all. It is only the outer ear that cauli affects, and equilibrium will only be affected if massive trauma occurs, creating build-up of pressure that could possibly rupture the ear drum. Although this is highly unlikely and has never happened to me or any other fighter i train with or know through the sport.
The biggest issue is the closing of the canal which makes in ear headphones useless, not to mention muffled sound all the time. But it is a badge of honor that shows you have put your time in at training and fighting, and is almost a secret code to spot another fighter or grappler when out.