[ronster]

The LN IMS bearing is a ceramic bearing made in Japan according to Charles Navarro of LN and, as has been mentioned, is an open bearing that allows motor oil to lubricate it. Ceramic bearings were tested by LN and shown to outlast metal bearings 5:1. LN does recommend a 5-40 wt. oil instead of the 0-40 wt. recommended by Porsche and a 5K mile oil change instead of the 15K recommended by Porsche.
LN has recently marketed an IMS Guardian that detects metals in motor oil that could indicate an IMS failure. The technology for it was developed from similar sensors used to detect failure in aircraft motors
Pelican is, or has, marketed a replacement IMS bearing but, correct me if Im wrong, is not a ceramic bearing.
As far as the frequency of IMS failures the only one who really knows is Porsche and they are not divulging that information.
Fortunately, or unfortunately, there is a plethora of information on the internet that may possibly be misleading depending on who publishes it and what they have to gain. Typically you will not be reading testimonials as to how long someone's motor lasted.