Training in mail isn't done very extensively in the historical European martial arts community since we don't really have any surviving medieval European fighting manuals from the earlier centuries when mail was the sole or dominant mode or protection--say, before the turn of the 14th century. Even if we extend the definition to the middle of the 14th century, all we get is MS I.33 and it seems to be teaching unarmoured duelling rather than armoured sword-and-shield work. That being said, William Short's group (affiliated with the soon-to-be-closed Higgins Museum) has been doing their own reconstructions of Viking combat techniques based on a mixture of Icelandic sagas and hints from much later manuals (principally Meyer, from what I see), and you might be interested in checking their
site out.
As for what little experience I have myself, I find that a plate cuirass is less cumbersome than a mail byrnie since the latter--if properly sized and worn with the correct undergarments--puts virtually all of its weight on the hips, leaving the shoulders free to move with hardly any encumbrance at all. Coverage is a problem, though, since it's generally more difficult to shape plate to cover the insides of major joints than to use mail voiders (or just put on a whole mail shirt underneath), so it's not surprising that a mixture of plate and mail hung on for so long (well into the opening decades of the 16th century) even in the complete suits of full-fledged men-at-arms.
While we're at it, have you seen Ian LaSpina's video? His armour is a plate-and-mail harness from the mid-14th century and he devotes a substantial amount of time to a discussion about his mail haubergeon (and how he compensates for its weight) in the middle of his arming sequence:
http://www.youtube.com/watch?v=9ybgJF02WdE