Just like to put in my 2 cents worth,
I think that all in all the WB is a good, solid, and very user friendly rest. I do know that there are some sacrifices which are made in the use of this rest, (fletching contact, speed loss, possible freezing issues) But overall I think it is a good serviceable rest which will perform well when used for what it is intended.
I personally do not own one,

Not because I worry about freezing etc, but because I have an old martin plunger/flipper rest that migrates from bow to bow with me (I know, I know, I need to pull it out of the jurassic age, but I love this rest)
I have personally been to Len's archery shop here in Maryland on many occassions, And I speak with personal knowledge in saying, that Len knows what he is talking about. He is most certainly up to speed on all things archery. More importantly I don't think that Len has a dim view of the WB, I do think that Len believe's that it is more important that we as archer's / bowhunter's remain informed about the different products that are on the market and their potential problems.
I respect Len's opinion on all things archery, for the same reason that many people respect my opinion on deer hunting & archery because of the fact that I speak from experience. But after everything is said and done, I make my own choices. As such, if I choose to purchase a WB it is Len's responsibility to inform me of that rest's pro's and con's, after that it is my choice on whether or not I am going to lay down some greenbacks or not.
Whatever rest you choose, make sure you know its limitations, and if there is a problem either fix it, or know how to fix when the need arrives.