My short version....over all the coils mentioned, id take the 7"dd...as tested on my mx sport and m6. Didn't have the 6x10 or 9" open frame to test, but also have the 6" concentric shooter and 5.3, but nearly all tests ive run on the nail board or in ground inform my decision. I dont spend most of my time in dense iron, but ive used it successfully in Nevada and in Lone Arch and other gt's.

I wont call it an opinion as its informed by several years of experience using only these machines, so i guess that means results and interpretation vary by user.

And btw, i cut the cable off my 6x8 sef to rewire a better, older coil. Of the 10 or so coils i have for my various whites machines, the 6x8 is the last one id use. Just blah performance all the way around.

If anyone wants one, you can have whats left of mine!

Zincoln