I've touched on this previously but having read this compelling article it further convinces me the "old fashioned" approach works best.

Many recruiters will search LinkedIn and throw out emails in the vague hope someone, a) checks their (often personal) email accounts daily and b) feels compelled to respond.

There is no personal touch to this and I fail to understand how a relationship can be forged.  It has a place, and, for me, that place is if targetted candidates do not return calls.  

Although time consuming, employing a good old fashioned headhunter is the best approach - that is if the client sees the investment in the vacancy and service.

I am very confident in talking with clients half way through a search regarding how the process is running and what the market landscape looks like.  The reason being, hand on heart, I have approached initially via the phone and latterly email / LinkedIn.

I will get back in my (old fashioned) box now!