Assuming no bugs, FLAC is truly lossless in both the compress and uncompress directions. It's easy to verify this yourself by comparing files bit-for-bit. As an extreme example, you can download a FLAC from, say, HDTracks.com, convert it to ALAC, convert that to WAV, then to FLAC, then to ALAC, then back to FLAC, and the bits will be the same.
I take the point that, eventually, a library may become obsolete and that an unintentional error causes an old FLAC file to be unreadable sometime in the future. This is unlikely to be a "sudden" thing; you'll be able to run the old decompresser for a long time (e.g. you can run DOS applications in a VM on Windows 7 x64, spanning many generations of technology).
Having said that, it's a matter of personal preference, somewhat outside the realms of hard science. The bits are the same, but I guess that it's possible that the act of decompressing a FLAC loads a CPU enough to cause timing issues in the outgoing bit stream; at the same time, the act of reading roughly twice as much WAV data versus FLAC from memory or a hard drive might have similar effects. There's really no right or wrong answer, and storage is cheap: 1000 albums are 600GB in WAV, 300GB in FLAC, i.e. $55 or $28 worth of storage, twice that with a backup. Big deal. In due course, you'll have a $5 thumb drive with this capacity.
The psychology of high-end audio seems to be as important as the science, and arguing about that is generally as effective as trying to teach a pig to sing: at the end, you're annoyed, the pig is annoyed, but you still don't have a singing pig
). I am really digging the combination about 30 minutes in. Dave (davo50) mentioned that he pretty much burned it in over the past 3 months. 
