I used to use dip sticks in my 22, don't have them now in my 44. An engineer friend hated them as said they could damage the sender and introduce crap into the fuel tank if they were not totally clean. I don't miss them now as I believe that: 1. The guages are fairley accurate. 2. If you fly the heli on a regular basis you know the way both guages go down together, so if one was faulty you would know. 3. You should know your fuel burn and keep accurate records of when refueled etc anyway. 4. Finally you have 3 things to go wrong before you fall out the sky: 2 guages and a low fuel sensor, all independent of each other.
I speak with regard to my own machine that only I fly, sure it might be different at a school, but point no 4 still holds!