The Recovery settings change the 2 filters by turning them on and off, Fast would be no filters on while deep would be both filters on. Now selecting both Fast and Deep settings you have say F-1 on and F-2 off, and having both Fast and Deep un-selected you have say F-1 off and F-2 on. So is there a difference? If there is then it would be in the filters, F-1 would have to be deeper or faster that F-2 and in knowing this we could make an educated decision on which filters would be a bit faster or a bit slower than the other and how you might want to set them.
I asked before if anyone knew if the filters were different, I would think they are because the settings are available and if they didn't make any difference then why is the option available. For fine tune hunting this would be nice to know even if it was only a slight difference in recovery.
I've read were some hunters like to just use one Recovery setting and that's that, but I have used both Fast and Deep and find that they both produce different and separate results at any given site. I can go into a site and only use Deep for a few days finding 10"+'ers and the usual 6" to 10" targets, then after things thin out I will go back over using Fast and then get many more coins but differently placed, these will be closer to the surface maybe as close as 2"s at times and though still able to pick up the deepies they are not generally deep as they were if Deep mode, there are more found closer to trash also in Fast mode.
The important thing is that this also works visa versa, if I first go in using Fast mode then my finds are the same, closer to the surface and close to trash, deep but not generally deep. Then going back over the same area this time in Deep mode I would again start to get the 10"+'ers and the usual 6" to 10"ers with no noticeable difference in getting the close to trash ones. But I would add that in Deep mode I do get targets very close to trash but not as close as Fast mode, just as Fast gets Deep but not as deep as Deep mode.
So, I believe that Fast and Deep must both be used individually and thoroughly at any given site. Because of the way in which my area was wiped out by previous hunters you have no choice but to favor DEEP mode over FAST, but even though I do favor Deep I have found that Fast mode is also an absolute must use, if you don't use both individually I guarantee your leaving more goodies behind than you have to.
Hope this helps a bit. You can check out a Recovery Mode Chart I put together on my Charts page by following the link below. <b>While your there you can mouse-over the 'olde detector' pattern and watch the coins and rings suddenly appear.</b>
GL/HH