I am not using recovery fast right now. But reading andys book it said it can change the target id accuracy? how many of u run this and does it effect target ids?
I only use it in a junky area with reasonably shallow targets. It helps a bit picking through the iron junk. I haven't really noticed any major change in target I.D. but iron infested sites are tough hunt and I generally dig anything with a high tone. (I run it in two tone ferrous at those sites).
I answered this on my Big Boys Hobbies forum for you but NEVER use fast. Just slow you swing speed in trash. Fast degrades the audio and #'s bounce to much. Makes good targets sound iffy.