Personally I like to wear my hose 3 finger widths below the knee cap. It feels more comfortable there and I get a double fold on my kilt hose tops. I like to wear my kilts just touching the of my knee but I have one that dips a little lower but not by much.

As for too high... Well, your either wearing your host too high or your kilt too low if your hose vanished underneath your kilt!!!