4 bones per vertex weighting. Has become a Pro only feature? On the beta page it says:

Quote:

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V6.60.2b

MEDB can now import FBX files with an arbitrary number of bones per vertex. Multiple bones animation can only be imported, but not edited in MED. The number of bones per vertex is visible under Model Properties. The engine now supports up to 4 bones per vertex. The number of bones per vertex can be restricted by setting the max_bones variable.

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The trial version on the download page is 6.40 so you can't try these new features. Don't think it will become a Pro only feature? Hope not!