Safe & Kv, I think you're missing the bigger picture here...
A stealth market in domain names does nothing to help your and everyone elses domain sales, because such stealth keeps the secondary domain market, premium domain prices, and, in general, true domain value, from public view.
For long-time industry participants, the value of good domain names is a settled issue. (Note to newbies: that's good domain names as opposed to just domain names in general.) However, the larger public--and larger business world--is stll very unevenly informed about the value and utility of domain names, particularly as marketing tools.
Having a good, extensive public record of significant domain name sales would benefit domain brokers by making public knowledge how much good domains really sell for, and the reasons behind their value: this would, I believe, sustantially bolster and improve good domain value, and thus increase domain sales in both volume and price point.
Directly related to this is the benefit of making ordinary internet consumers more aware of domain names, which would further attune them to using domains as primary contact points for businesses.
Greater publication of domain name sales would also stimulate media interest, and would stimulate adademic interest, so that more research would be done into the value-added elements of domain names.
All this would serve to raise everyone's profit, including yours. Business may be good for you now, but it would be even better if your buyers bought in an environment of full domain name value realization--an evironment in which the conventional business wisdom fully understands and appreciates domain value. A domain sale you made for $2500 last month could have been $5000, $10,000 or even $20,000, if everyone on the buying end understood just how powerful a marketing tool a good domain name can be, and how this one-time investment becomes the central point of a business' marketing strategy, serving as brand, message, contact and online location.
Worried about others contacting your clients? Every vendor in the world could say the same thing. Unsolicitated communication is a reality of the free market, and in fact is sometimes responsible for good business. They will survive.
You say you have enough data from your own sales? Not unless you're microsoft does such a claim make any real sense. Your sales are a tiny fraction of the total market--you could be substantially underselling and not even know it. Now, I know that you, safesys, in fact do have a good take on the market, and keep in contact with a large domain broker network, but your sales, as I explained above, would be even better if your buyers understood the full value of domain names, which would best be accomplished by creating a good public record of the domain secondary market.
Success tends to be conservative, and many successful domain brokers seem to be worried about "rocking the boat." But this is a classic case of not seeing the forest for the trees. Transparency and good reporting are the universal fundamentals of healthy, robust markets in any economic sector.
Good domain names have real value. We know they work. Making sure the rest of the world is equally informed would benefit every stakeholder--sellers, buyers and users--in the world of domain names and the internet.
Miles