Ace 250 Coil

I currently own an Ace 250 with the stock (6.5"x9") coil. I've read, and heard from others that the 9"x12" coil can read depths of up to a foot, and those extra 3 or 4 inches that the 9"x12" adds on are EXTREMELY benneficial. I'm just looking for some insight on this from other Ace 250 owners. Is the $85-$95 upgrade worth it? ($100-$115 with shipping plus coil cover)

-Rob