I have to admit I don't really hear any difference between FLAC and high quality lossy compression. But: I do experience problems converting from one lossy format into another. (For example I used to have MP3-files, converted them to OGG one day, then later I found AAC is better for my mobile phone etc etc ...)

So I now keep music as FLAC on my computer and can - if necessary - always re-encode to other formats without quality loss. (Without any quality loss that I notice, that is.)