Hi, Plugger,
I was one of the field testers on the X-Terra's, and I also hunt the beaches here in S. CA pretty extensively. I haven't posted much of late due to the fact that I've been laid up with a very slow healing broken left leg for the last few months.
Please take a look at my post via the link below:
http://www.findmall.com/read.php?55,312654,312654#msg-312654
In my opinion, and I have stated this before, there has been a great deal of attention devoted to GB #'s that to me is a bit of overkill. I have found the 50 & 70 to be very stable, forgiving machines, and to be honest, I could care less what the GB #'s are at any given time. Sand here in S. CA varies in mineral composition on both the wet & dry. The main thing that I am concerned with is whether or not I am finding stuff, and at what depth.
When I hunt the beaches here with the 50 or 70 I set the GB & start swinging. Then every so often I check it & re-GB. To be honest, as the manual states, I have found the sensitivity to be the main factor with regard to the machine running stable. Just don't run it too hot--the X-Terra's are very sensitive, especially with the HF coil. I would not recommend running tracking in the wet sand as the continually changing salt content is tough on any ground tracking detector. You can try the beach mode, which I found to stabilize my signals somewhat.
Most importantly, I would urge you not to overthink the X-Terra. Even though it has a multitude of adjustments, what I love about it (and all the X-Terra's) is that they are fun & easy to use. Just set it up and swing, then check your settings every once in a while. You should do just fine.
Any more questions, feel free to post or email me at wpaxt@aol.com.
Bill (S. CA)
P.S. Oh, and don't forget to overlap your sweeps with the coil since it's concentric.