Whites or Garrett?

Max is right, a 12 in coill on a soveriegn is DEATH. Except if you've got a gold ring 6 ins away from a tab, then you're going to miss one or the other 'coz you're likely as not covering both and the detector's got to make up it's mind and it doesn't know if a tab is more valuable than a ring or vice versa. But on the beach, the density of targets isn't so great that this is a big issue. Yep, go for the bigger coverage and depth with a 12!!! As to auto or manual, I advised auto just because I know a guy who FINDS stuff in a way you wonder what you're doing wrong, and he told me Auro on the beach. So it's just heresay. Could be once you really know what you're doing, manual is the best option. Anyhow, the fact is that once you're in the top end of the market, a lot of machines do the job. The Sovereign happens to be switch and go so even an idiot like me can use it out of the box. The other machines have a steeper learning curve in my opinion.

I got to say I've never met anyone in Europe using auto unless something forces them to.
Back to the Fisher 1280. To use it on the beach you have to run discrimination up to balance the salt and sensitivity down. This does not lead to the best results. Even then on many wet beaches if you dig a hole the machine will detect it as metal. The Fisher Cz's suffer the same problem if used in ground mode which is the only way to get small deep items on many of our beaches. Use the ground balance as though detecting land and it works fine but when you do your recovery the hole sounds off as well as the detected item so you either have to get the item out with the first spade or two of sand or switch back to beach mode for pinpointing.
I'm not suprised the CZ 20 was discontinued as the none waterproof CZ's were so much better. The 20's two advantages were a waterproof case and doubled up batteries. No more performance but an extended detecting time before battery replacement.
With the Sovereign like anything else if you want the gold the ringpulls have to be dug so no problem