Is it a bad idea to have your info publicly available when selling? Some extensions are expensive to maintain as is. Suppose you wanted to sell now and not pay ten bucks(Godaddy) . Is it really critical to have that private registration?
You have to ask yourself why is it important for you to have it. Why would you think it's critical? You decide by yourself how much privacy you want and who you do and don't want to know that you own a certain domain. The only other reason I would think you would want to have privacy is if your domain is part of a blog network you own and you don't want the big G connecting the dots and deindexing your network. If you're selling the domain then it won't be a part of your network anyway. Bottom line is that if you're selling the domain it really doesn't matter since the ownership on the whois will change as soon as the domain is sold.
I would recommend not using whois privacy if you intend on emailing people to purpose a domain you have for sale. If a potential buyer went and checker (and yes, many will) and see that the info is locked they may be hesitant. On the other hand, if they look and see the same email listed there is the one you are communicating to them with then they would feel much more confident and secure that you are the real owner. If you're going to purpose domains to people with whois privacy enabled then don't be surprised if the few that do want to proceed with you request that you an Escrow service so they feel more secure.