I've been working on a tool to, well, "destroy" the structure of an .it file you give it in such a way as to reduce the file size. Unfortunately, XMPlay has issues loading the sample data, and so the samples sound all wrong. I have tested this in XMPlay 3.4 and XMPlay 3.6 using Wine (and I assure you, it is not a Wine issue).
I'll probably get shot by the forum software if I attempt to paste a link, but here's a link to one which DOESN'T have IT214 or IT215 compression:
http://pubacc.wilcox-tech.com/~greaser/mods/deja_vu.it (I hope I got that right). Later versions of munch.py have IT214/IT215 sample compression, but I believe those would be handled by XMPlay otherwise.
And before you ask: Yes, it works fine in IT 2.14p5.
P.S. If you're not doing it already, if an IT21x sample block fails, IT 2.14 will still attempt to decode the next block (if I recall correctly). Modplug-based stuff will stop decoding the sample altogether.