Monte------It looks like you have 5 detectors mounted with "small" coils---and---3 detectors mounted with mid-sized coils (5x8" + or -) mounted full time.-----Why so many of the same size?----Do you see the respective detector/coil combos getting all that much difference in performance to indeed warrant having all of them?--------Myself--for small coils---I have the Nokta 5" DD coil for my Multi Anfibio that I recently purchased from Joel & I just can't say enough good about that combo--it's just "killer" in the trash & iron.------I also have the FT 5" DD for my F-19 which is a highly productive combo in sites like just mentioned.-------In mid size coils---I have the Nokta 9.5x5" DD for the Multi Anfibio (the jury is still out on this combo)--I need more swing time with it to make a decision.----Also have the Nokta 7" concentric for the Anfibio & it's proving out very well in certain scenarios.--------Lastly (in mid-size) I have the FT 5x10" DD for my F-19 which I find is an excellent combo.------------Del