So got the smart tweezers in and did some readings off of the delta coils I have.
10x12 widescan Tx=21.6mH Rx=1.25mH
8x11 dd Tx=23.7mH Rx=1.23mH
Cors Shrew Tx=21.6 Rx=1.18
8x9 Concentric Tx=19.8mH Rx=1.25mh

Best performing coil for sensitivity is the concentric.
Descent depth for size is the Shrew
Deepest is the 12x10
Worst performing coil that lacks sensitivity and depth for its proportions is the 8x11 but that is on the Tejon at 17.5khz

Tossed the Shrew on the Cibola and tweaked the gb trim pot a little so it was very well ground balanced for my area and the machine runs fantastic. Really fun picking out coins from high trash areas without giving yourself a migrane.

Curious how the 8x11 may react at the beach so when I get a chance I'll test it out. Might either be out of wack enough to handle the salt better or worse.... not sure.