What Lee said. The FLAC/WAV difference is also not unique to this player. It will depend on how critical you are and revealing the kit. XLD is great for MAC. For those that have used the wrong tagging on their flac files, this is from the Soundforge flac page. Like Lee has noted, they're not difficult to change but...
"As a convenience, the reference decoder knows how to skip ID3v1 and ID3v2 tags. Note however that the FLAC specification does not require compliant implementations to support ID3 in any form and their use is strongly discouraged."
It will work fine with one of those but it's not part of the flac spec.
Since flac is open code, sometimes an encoder gets a 'better idea', tweaks the algorithm and it becomes not fully compatible. Usually decompressing and using a different encoder cures it.
Edited by goodvibes - 1/15/13 at 4:35pm