John,
Both have their places. For example, the Equinox will do better than most VLF machine in wet sand and salt water. If you need a metered machine for coins in new playground, tot lots, etc. the Nox will work great. Where I find the Vista X to be exceptional, is old homes, CW sites, any place that has "been worked out." The depth is great and separation is even better. Most people will run too much discrimination and walk over non-ferrous targets that they should have gotten. Beds of nails are fun with this machine and slowing the coil down and the detector "sees" good targets in the iron. One reason why this machine works so well is that is a hybrid of sorts. The detector is analog but the audio is digital. Analog filtering is limited by specific filter for certain freqs but with digital filtering, the shape of the filter can be changed.**
With the X, I have been using the stock 11" coil and was going to use the 6.5 x 8 XS coil but sold it. Joe Huber in Maine does the warranty work for North America. Any questions, let me know.. HH Richard
** As a HRO, I used analog equipment and with normal signals and filtering, I could clean up a bad signal. But now with digital radios, they can actual go into the noise and pull out signals that I couldn't hear with the analog equipment