F70 vs F75 vs F75LTD???

I have always heard the F70 had the same depth as the F75.  What settings are people using when they measure the depth.  I have only used the F70 but there are so many ways to increase the depth that I sometimes wonder if it can't beat the F75.  Obviously, maxing the sens out at 99 makes it deep.  Then drop the disc to 0 and gain more depth but the F75 can do both of those.  But then there is the threshold setting the F75 doesn't have.  Max that out at 9 and you get an improvement measured in inches.  Is that the same as switching the F75 to JE mode?  Now you can change the speed to slow which again gives at least another inch.  Is that similiar to the LTD boost?  Its so hard to get facts because every situation and every soil is different.  I know most people hate airtesting but that is about the only test each of us can do where all variable are constant.  With all settings maxed and using a Mercury dime dated 1938 in EF 45 condition I am able to get a solid easily identifiable signal that ID's correctly at a repeatable distance of 11.25" using the 11DD coil.  How does this compare to other machines that are maxed out?       

Hmmm, too much to think about.  I am impressed by the F70 for several reasons, depth is not one of them yet.  Using the 11' DD and while my best silver with it was a '26 SLQ at almost 8 inches, and it readily id'ed it with a solid 87/88, I'm wondering if it had been an inch deeper would it have responded the same?

The guys who have used both seem to indicate the concentric coil is better at ID and it seems intuitive that the concentric would be better at depth.  But until I get the coil over a 10 inch deep coin or better and read the info the machine is giving me correctly, I don't know.

The guys who have used both the F75 and the F70 seem to stick with the F75 from what I'm reading.  That makes sense too, it being the big brother of the F70.  I did manage to figure out my shortcomings with the C$ by learning the F70 to this point, seems they perform very similarly and have very similar settings.

As to cranking the F70 out in every aspect, I don't know how many if any sites would be friendly to that prospect but so far I'm happy with the unit where and how I use it.  Good thing too, not a "keepin' up with the Jones' " budget for md'ing in this household these days.

[Goldfinger]

I know most people hate airtesting but that is about the only test each of us can do where all variable are constant.

Not with fluorescent lighting, appliance motors, powerlines, cell phones, house wiring, nailed v. glued flooring, metal on your person, the table, the walls, etc., etc..  Air tests are as variable as soil tests and slightly less reliable.

All they tell you is how well a detector will do against flying coins.