I've lately registered a couple of domains as "private registrations", which means that my contact information is not displayed in the whois info. This is a service provided by several major registers nowadays. There's nothing special with the sites I'm using these domains for, they are not adult sites, not gambling or anything like that, I just feel a bit uneasy spreading my contact info all over.
How about when an advertiser wants to do a deal with you? If you don't have the info there, how can they get in touch? If you have your info on the site as well - then that defeats the object of a private registration anyway!
I've no problem with private registration services like the one you mention; if somebody wants to get in touch, their first port of call will more often than not be the actual website, rather than looking up the WHOIS data. Of course, not having a website does then become a minor problem!
In terms of e-mail contact, I'd have thought that most private registration services would simply forward any mail received at your private WHOIS e-mail address, meaning that anyone who wanted to send a mail to this address would still be able to get in touch with you; this is how the private registrations I have work and don't see it being too different elsewhere.