The DFX is an underrated beach machine. Saying that, you really have to know how to set it up correctly. There are several options that need to be bumped up like preamp gain, AC sensitivity, while others need to be adjusted for the conditions like, sweep speed, recovery speed, filters, etc. If there is a lot of iron, correlate mode may be better than best data....all that good stuff ! Plus, you have to know what to listen for. A lot of deeper targets don't sound sharp and clear on the DFX, may break up and sound 'iffy' but you can gain a lot of information listening and checking the signagraph. Also, you should really dig everything that hits deep on the beach anyway.
Out of the box and with minimal set up, the Sov GT is better. Even after all the tweaking and setting up of the DFX, the Sov GT is probably still better. The DFX may hit smaller gold better in the dry sand if you decide you wanted to hunt that area because you can switch it over to 15kz frequency for better results on the lower conductive targets.
The stock 10 inch coil on the GT is probably one of the best coils you can use on it so you don't have to run out and get different coils to get great results.
Saying all that, the DFX has gotten great results on salt water beaches.
JC