kenozaguy,
I have the 9X12 coil for the Ace and I think it might get you another inch or two but nothing substantial. I use it occasionally but the site I have has many roots and vegetation that it keeps getting caught in something. I should pick up the sniper coil but I just switch back and forth between the standard and larger. Its hard to tell how good it will do unless you have it on and it picks up a target at your site and then you switch to the standard coil and see if that can pick it up also. I will have to try that but I know that doesn;t help you too much since you want to know if you should get it. If you have the cash and don't mind that it might not be exactly what you were hoping for , then get it even if it is just for another coil. I know my standard one has chips and scratches on the bottom and I finally got a cover for it, but if something goes on the standard I have the 9x12 as a backup.
Sorry if this doesn;t help you decide, just wanted to express my feelings about the coil.
HH
Funkman