As far as the cost of the coils, yes they are more than the run-of-the-mill VLF or multi-frequency coil but with only two to choose from, your max outlay is somewhat limited. People do have piles of coils for other detectors but with the electronics in the coil, do not expect to see a number of after-market options produced for the Deus. In testing the stock coil in amny different areas it handles trash as well as any 8" DD coil does yet still provides good coverage and the depth one would expect. The larger coil adds coverage and some increase in depth although the biggest advantage is the coverage - well suited for the beach or open areas as others including Barry have stated.
Coil prices can pretty steep . . . . look at some of the optional coils for the GPX detectors whcih already cost 3X what the Deus does . . . . Nugget Finder coils run up to just under $600 each with no electronics in them but if they work, they sell - that simple.
I know several X-Terra users that have a pile of coils that cost more than the detector itself . . . . . but if they fit a niche, then they are worth it. If you look at the need to buy 3 coils to get the 3 frequencies on the X-Terra and the Deus offers 4 out of the box, that should play into the mix (and yes Larry, before you post that White's also offers different frequencies with the stock coil, I was only showing that you get some versatility with the Deus and a single coil).
It comes down to what you want the detector to do and what factors are important to you . . . . . no one, including me, has said that one should sell whatever they are using and grab a Deus . . . . it is simply another high-performing detector that joins the ranks of others on the market that might appeal more to people that found what they felt was more important to be lacking elsewhere. Even before the Deus was introduced formally to the US market, there are people that swear by Minelab units as well as White's, Fisher, Teknetics, Garrett, Tesoro and DetectorPro among others and they all seemed to be finding some pretty impressive targets . . . . . sort of like the "Ford-Dodge-Chevy" arguement . . . . .there is no perfect detector for everyone . . . . . the Deus simply offers different features, capabilities and performance . . . . . which may or may not be what you have been looking for . . . .
Andy Sabisch