Thanks all for the advice, will do a little more research.
Think I’m still leaning to the Excalibur atm.
If you love your Sovereign GT on the sand, you'll love an Excalibur in the water.
An Equinox would add a visual screen capacity, very useful in high target areas where you want to (relatively) conclusively identify or exclude certain nuisance targets. The Equinox would potentially provide better low conductor sensitivity, and also the ability to use a single frequency which could be quite helpful in dry sand or in freshwater areas.
But an Equinox does not have the simplicity of use of an Excalibur or Sovereign which have simple dials and switches to provide adjustments on the go. With a screened machine such as Equinox you have to push buttons and look at screens. Admittedly the Equinox interface is much simpler than something such as the CTX, it is still has a screen, and I hate screens.
The ongoing Equinox mania may produce some good deals with used Excalibur's, you may want to consider a good used Excal if you can find one from a reliable seller (if you can find one with upgraded headphones, that would be especially sweet!) I also suspect that the Equinox 600 will also begin to appear in the secondhand market, as some detectorists have purchased the 600 out of frustration with not having the 800, and may eventually decide to upgrade to the 800.
If you hunt saltwater beaches, you may want to consider a waterproof PI machine, but these don't discriminate out iron, and can be virtually impossible to use in certain high target density locations. The PI machines also have a learning curve, but if you've used all metal/pinpoint mode on your Sovereign GT, you're actually halfway there.
Good luck with whatever you choose!
Charles