I waterproof all my scale running rigs with ballon.
All of my rigs running Tamiya TEU101BK ESC, no overheating issues at all.
In fact, they not even get warm in my rigs..
Just use ballons with clear sillicone in the end of the ballon, make sure that you rub the sillicone around the wires so it 100% water tight.
Use a small zip tie at the end and a second one a 1/2" apart from the first one, with a ring of sillicon between them, that makes the esc or rx 120% waterproof...
I only use cheap servos so I don't bother waterproof the at all...
My XC Pajero uses a Hitec 645MG and it has been driving 10" under water several times, and I have opend it up a few times to check for water and I have only found 1 or two drops of water inside the servo so I do not see the need to waterproof that one...
In fact that is my longest lived servo to date, all other servos are crap in comparision....
My friend has a Hitec digital servo that the previous owner has greased all up to make it waterproof, but it is slooooooooooow...
And here are a water running wideo of my last 2.2 rig (orangered Jeep) and my mate with the blue Jeep...:mrgreen:
http://vimeo.com/7445680