What is the advantage of re-ripping everything in FLAC and then converting to MP3?

The advantage of ripping to to FLAC is that you will never have to re-rip your CDs again. FLAC is lossless so once you collection is in that format you can re-encode to anything.

Suppose your empeg has a 10GB drive in it today. You may encode your MP3s to 128k so you can fit your whole collection on there. Once you upgrade your drive to 80GB you would now have room for higher quality MP3s. Would you rather re-rip all your CDs or just run a batch re-encode on your FLAC files?