Most free giveaways had portions encoded with LPC or WXC compression methods. Neither of these Waveform formats are supported by the Montage converter.

See: https://www.yamahasynth.com/forum/finally-montage-is-fully-compatible-with-motif#reply-27555

... so when you read that Motif XF data can be converted "without a hitch" -- you need to read the fine print which says: except for a hitch for promotional data that uses certain formats.

The notion that this is for copy protection is interesting. Because, from the discussion Yamaha presents, promotional/free stuff would be protected while paid-for commercial stuff is not. Seems backwards if there was ever a copy protection motivation to those formats.

Seems more likely that WXC perhaps compresses data down smaller than other formats (maybe LPC too -- and maybe they are both more lossy than the other formats) -- so a slight hit on sound quality - you get smaller libraries. It's speculation but the copy protection theory just doesn't make a lot of sense to me given what is protected and what is not.