Brian,
If you have the time I would love to have some air test numbers from that little NEL Snake coil. All we need to compare is to have the same settings and the same target. I am not saying that the air test numbers are max depth or distance from the coil. I just picked those setting numbers because the detector was running pretty smooth with all coils and give me a good snap shot of what each coil will do compared to the other coils.
So here is a picture of the air testing I have done with my F75Ltd upgrade and the coils I have.
I done a factory reset and selected 90 DST, disc @ 15, sensitivity 80, and the target was a clad dime. As you can see I got a number for every processor, but I will take what I can get. I did use headphones and I would swing the dime past the coil and move it away until it was not a dig able signal and then back up until it sounded dig able and record the number.
You will notice that my testing shows that the 5" and 6.5" elliptical are really close to the same depth. My all around favorite coil is the 6.5" that I got off Jim a while back, and as Jim said it does like the woods.
I did check on line at Show Me Treasure and they have NEL coils listed but not the snake for the F75. I would guess if I would have contacted them by email they may have more than was showing.
Thanks Ron