I've been using Tag&Rename to edit the ID3v1 tags in my MPC files. Of course, it's annoying that you can't use long song titles, etc., with ID3v1. I've played around a little and added ID3v2 tags to some MPCs, just to see what would happen, and have had no problems other than the Winamp plug-in won't display them.
Since I've been reading a lot of info about APE tags and MPC, I went to the Tag&Rename website to see if they had any info about possibly supporting APE tags in upcoming versions. I noticed that one of the new features in the new 2.1 beta 2 version is support for ID3v2 tags in MPEGPlus (mp+, mpc) files.
I would really love to use tags that use long fields and I would love to use Tag&Rename (since I paid for it). Is there really any risk if all I am adding is longer titles, etc. I wouldn't be adding cover art and all the other junk that you can with ID3v2.
Also, I sent a short email to the Tag&Rename developers asking if they had plans to support APE tags in the future.
http://www.softpointer.com/tr.htm