Plural is normally worth somewhat less than the singular version of a domain but it depends on the name. Shorter the better but not for many types of web sites. Try to get them both for various reasons. As for traffic, it could vary for many reasons.
One example is:
I own the singular version of a generic one word business domain and it is a dot cc generic domain to boot. When the website of the exact Plural name advertises, I get surges of traffic to my domain. I would speculate that I am getting a substantial portion of their business on a regular basis.
I offered them the domain name at a reasonable price several times but they refused. They actually hung up on me (bless their hearts) about the fifth or sixth time I called them, to sell them the name that they really need!!! Just trying to help them is all.
Not only dot com's can make money parked. CcTLD's can make revenue as well! I lucked out and reg'ed the domain after the company went under. It came at page rank 1 and ready to roll as it was an online business several years. Even the blind chicken gets a piece of corn once in awhile.
"Oh well", I suppose I will continue to borrow their high conversion ratio costumers at virtually $8 a click thru if they don't want to see the light and buy it. It has made as high as upper XXX a month ppc revenue over the past 3 years. Just a cash cow. It makes me feel a little bit guilty about taking their business as they are probably losing hundreds of thousands of dollars in gross revenue a month to my domain name that makes only low pcc revenue. But what can I do?
Many end users need to be taught via the phone in order to sell them, more often than not. They are not always the brightest stars in the sky when it comes to domain names. We are not salesmen as much as we are teachers, it sometimes seems like to me. Excuse me for digressing a little.
Namaste
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