Most of us don't have much of a use for the Ground Grab Elton, I think it is used primarily in prospecting in ground that that is very "hot" and changing where Locktrac is used. The MXT has one of the best Ground Tracking systems on the market and that is what makes it ideal for the weekend prospector, relic hunter and coinshooter alike. For those who hunt with tracking locked, it is just a button push to update the ground balance instead of pumping the coil. Here is what White's has to say about it:
Ground Grab: Provides a convenient way to update ground tracking from a locked setting, or from a tracking setting, temporarily lock ground tracking for multiple passes over questionable signals.
I can see where those who hunt with tracking on would benefit from temporarily lock tracking when investigating a deep questionable target because the tracking is so fast it could track the target out, but I think many users will GB and lock it in ground that does not change much.
I have not read the manual, so someone with the manual or who use the MXT Pro might be able to add more to the conversation. Pro users.......what say you?