I highly recommend the EMBRACE Earmount Lavalier Microphone from Point Source Audio. It can be worn over the ear or in the hairline with equal effectiveness.
They are far more durable than countryman and virtually student proof. So, if there is mic sharing during a show, there's less chance of damage. They will work with your existing packs (just order with the proper connector).
I am fortunate to have 30 of these microphones and I am thrilled with them.