If the Vx3 is like the V3i, I would question the deeper, and faster commentary. Not sure but with the proper programming and a decent aftermarket coil, I feel mine is deeper than my Etrac.
Having used both of them I would say the V3i. The V3i has a larger coil selection and probably always will. You will dig less trash with the v3i in modern trash sites. They both seam to be pretty close in depth. ID at depth and depth guage much better on v3i. In heavy iron trash the advantage would go to the Equinox.
It really depends on the type of hunting you do. If more of a relic/beach hunter than the Equinox. Old coin hunting at depth the V3i. I have an equinox 800 for sale right now for 825 shipped.