I don't think it's necessarily a case of when, but it isn't too uncommon. The compressor can be disconnected and even removed. Apparently it will throw a warning light but there is info out there on how to remove it. With the pre-facelift at least, the windows can delaminate causing unsightly white marks. So far I've had LS430's for 4 years with only one height sensor being replaced. Even these I see Paul Frost has them for £85, better than the £350 I paid. They can sometimes be taken apart, cleaned and resealed.