Personally, I would go with the 12x10 SEF. I hardly ever use the 15x12, as I have to turn sensitivity down on the wet and shallow water, while I can crank sensitivity a bit with my 12x10. The 12x10 is the best all-around SEF IMHO and has had me digging 1/2 way to China on many occasions. One time, I got a deep target and the hole I dug was so big that I stepped down into the hole. The top of the sand was equal to the top of my kneecap, which when I measured, was 24", so the 12x10 SEF will give your arm plenty of joint pain, lol. It's lighter than the 15x12, provides great coverage, easier to swing in water, and will go deeper than you really feel like digging. It's been on my Sov for over 10 years.