"What is your take on the concern of many business owners that if they put too much information on their websites it will give too much away to their competitors and leave no reason for prospects to contact them?"  

Jeffrey's response was that "When clients express this fear I ask them 'If a prospect knew as much about your business as you do, would they still buy from you?'  Most business owners after a short pause for thought response with a Yes!"  

In which case, why not try to answer all your vistors' questions on the website and then invite them to contact you to buy?  

Very interesting to hear this first hand from such a highly regard internet marketeer as Jeffrey.  

With the exception of commercially sensitive information such as price lists, I recommend to clients that they publish information on a "why not" basis rather than a "need to know" basis.  This might also include allowing indifferent reviews of your products to be published along side the favourable ones.  Buyers are not daft, they know that you can't please everyone all the time and will respect your for your openess and the way your handle criticism.  There is good evidence now that this does indeed increase conversion rate!