I hear your pain. In Aug of last year we replaced a year old WS-1400 that had sustained a nearby lightning strike, which took out its transmitter, with a WS-2902. I was favorable impressed with the WS-2902 although I did find that as shipped it was NOT moisture tight and during some intense rains enough moisture accumulated inside the unit to foul the transmitter until the sun dried it out sufficiently. I pulled the unit down and dried it out thoroughly and then sealed the gaps on top with silicone before reassembly. All was well until a few weeks ago when we had several days of very damp, freezing temp weather when the humidity sensor went down. At first it was intermittent, then it failed totally. I thought it might be a cold solder joint but when I pulled it down to inspect, I discovered that the WS-2909 uses a surface mounted IC chip for temp/humidity so nothing repairable. As was your experience, Ed wanted me to RMA the unit back. I contemplated the situation and came to the decision, at least in my calculus, that I wanted reliability and cost would be secondary. So I ponied up for the full blown Davis Vantage Pro2 Plus (6163). Yes, the cost is not trivial in the least and on top of the station itself additional hardware was required get the unit on the internet (USB data logger to connect to my existing meteobridge). Comparing the Ambient WS series hardware to the Davis VP2 is along the lines of comparing a really nice economy vehicle to a Merc S560. Each has a place and a value/cost proposition, but there is NO comparison in absolute quality, features, reliability.
AW offers a LOT of function for the buck and from my experience, their units are really quiet accurate, but the longer term reliability seems to be the trade off.