Well seeing as its my birthday today (happy birthday me lol) my wife has decided that my ageing E61i must be replaced and has bought me a new E72.. so I think I'm going to upgrade from the CK7W and either get the CK300 or CK600 kit..
Happy birthday Fahad! Go with the CK600, it's a great kit and I love it. Since you already have the CK-7W installed (still do?), you can reuse the Mic from the old kit and hook it directly into the new kit.