I have set up a 4.5 coil on my ace 150 and I am planing on leaving it there.As many times as I change the coil on my 250 I am afraid that I may be wearing out the connections or I am afraid in the field I may get a piece of dirt or small rock in the connections. I change it every time I go out.So now I just take my 150 in the car along with my 250 and I use witch ever detector the hunt calls for and for some reason the 4.5 feels better on the 150.What are your thoughts on changing coils so often ok or bad ?