IMS job half-done - My IMS was perfect when removed.

[mountainman]

My 2002 carrerra 4 IMS failed at 46K which I find absolutely reprehensible for a a high priced performance car. Never tracked and always carefully serviced. The last service was less than 2K miles before it self destructed with no debris having ever shown up in the filter and no other symptoms. Happened at 60 mph on a PCA outing. From the porsche dealer all the way to porsche customer service rep, everyone was very sympathetic but said that because it was out of warranty that was just tough. $20,000 later I was back on the road. Due to the number of failures of this part, I see this as a design flaw and a failure of porsche engineering to address it. It would appear that the only safe way to protect yourself is to spend $2K every 25K miles to put in a new bearing just in case. After venting a bit, let me say that I bought my first porsche in 1964 and I currently have three of them, so I have plenty of brand loyalty. I just feel that porsche has let us down in this situation. I now have 25K miles on the new engine and I really don't feel secure that I won't have an impending failure with it soon.
From my reading about the guardian a significant number of opinions are that when you get the warning it is probably too late to save the engine and you are still looking at a rebuild, but you have maybe saved the core. Are we better off just to have a milage schedule to spend 2 grand to put in a new bearing. If so, what milage would be safe?