That's fine Wolf, I looked at a few reviews on the Grey Ghosts and they didn't come back too good on the comfort side of things, though will differ from person to person. Your setup with the Grey Ghosts and WS4 has much more flexibilty and setup options. If the WS5 screws up, you are stuck with an expensive piece of kit to repair vs the cheap WS4 backphone replacements.
I've been mulling over a detector purchase for a while now to compliment my Explorer for difficult to detect areas (namely iron ridden spots), and something that was a bit future proof without going over board on the $$$. I have no real allegence to any specific brand, so always keen to try something new from other manufacturers, just as you have.
I Did consider an Etrac, but it's just too close in lineage to the Explorer to consider having both, and possibly end up with the same issues on certain sites. The CTX is just too many $$$ for me to swallow for a coin/ relic detector, plus the fact I don't beach detect any more is another deciding factor. The Deus sits nicely priced for even less that the Etrac through a deal I am currently trying to organise.
Will probably start with the 9" and upgrade later on to the 11" should I feel the need.