Well, I got sucked into searching fee bay for ace stuff for my 350, and see that there is a 10x14 DD coil available, as well as a 15x12 SEF butterfly coil. Would I get any more depth with either of these? I think I am just wanting to buy extra toys... just got my propointer in today, and ordering a sniper coil tonight.
Yeah, you'll definitely get more depth because they are larger search coils. I've always been a fan of the Detech/Excelerator search coils. I got that 10"x14" DD Excelerator for my wife to use on her Ace 250 back when it came out. She doesn't like to use it because she's not a fan of larger search coils. I play around with it sometimes on my old GTAx1250. It works great and it is much lighter than the Garrett 10"x14" DD search coils.

Happy Hunting!