I had a V3i for several years, have since sold it. Went to an Etrac, then a CTX. While the V3i screen was FANTASTIC and the wireless headphones were GREAT the change to Minelab, FOR ME, was a much better fit performance wise. Screen is better than an Etrac but way off from the V3i.
I hunted (with the V3i) along side a friend with an Etrac for quite awhile, after comparison on the same targets I went to the Etrac and now have the CTX.
I feel I gave the V3i a very fair use (3 years) but overall I have to say - FOR ME - the CTX is much better.
Again, I am saying FOR ME, others may have had the opposite experience.
I am currently selling the Etrac and also a TDI to get the Deus as it appears to do better in iron. I'm hunting a site with a lot of iron & silver- see the posts below. The CTX is constantly nulling in the bottom right corner but occasionally the silver pops out. As you can see from the posts it is doing very well in high iron.
Unfortunately the best suggestion is go start with one or the other then try the other. Depends on your ground, type of swinging, how much you want to adjust in the field etc. I have bought many detectors to try them out, if it didn't "fit" with me I sold it and tried another. Not sure where you are located but maybe someone nearby will let you try theirs out.
http://metaldetectingforum.com/showthread.php?t=248098
http://metaldetectingforum.com/showthread.php?t=246518