to be honest with you I've personally not heard any horror stories with lexus CVT's.. I've driven and known people who have owned some high mile gs450hs, rx400h etc with CVT's and 0 issues.
nissan cube we had was known for CVT problems but again, original box with some servicing at 150k km without issues.
personal view is this :
if you like how it driver, I would completely not worry about the reliability part of CVT's in newer lexus cars, and like
@sandys said, there's the 10 year warranty on top