The Erotic Highway
I've used various versions of the vibrating cock ring with fairly good success... 
I've used the disposable ones from durex and elixa(trojan), as well as one with replaceable batteries that go into a small bullet vibe which is attached to the top of the cock ring. It's a little bigger vibe than the disposables, but it's also variable speed.
Hmmm...D_4_u,
Habituation is not the same as addiction, but..if you get so turned on by vibrators that you ignore the rest of the sexual spectrum and its ability to turn you on, then yes, I would say that you eventually "lose" your skills in other departments. Remember that your brain is your most important sex organ. Both practice of what you do know and exploration of what you don't, all contribute to a more expansive sexual experience. If you automatically "tune out" when something else is being done to you - or, you do it to yourself, of course - then you might be shutting off responses you would normally have.
From anecdotal material, I haven't seen that men feel "threatened" or "upstaged" by vibrators. The average guy, for better or worse, LOL, has a sexual self-image that doesn't get perturbed by the presence of a vibrator in the bedroom. Au contraire, many men find it very exciting to see their woman please herself, or see her pleased by her partner maneuvering the joystick.
On the other hand, if a woman is verbally belittling her partner and making derogatory remarks and references to the superiority of a vibrator to the real thing, that could possibly dent a man's self-confidence. But n.b. that we are talking about explicit and repeated verbal remarks, and not so much just the presence of a harmless piece of electronics. Of course, exceptions to the rule always exist in some bedroom in this world, so...
Bzzzzz ,
the Love Goddess