I noticed the list of compatible libraries on Yamahamusicsoft is identical between MODX and Montage with one exception. Abstrakt Horror is not shown as compatible with MODX while it is shown as compatible with Montage. It's possible that a library compatible with Montage wouldn't fit in MODX if it uses samples that are too large to fit -- but this seems very anti-social for a library to consume that much space.
I wanted to check to see why Abstrakt Horror isn't listed as compatible with MODX.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R
Already got my response. It seems to be a goof and MODX should work fine with Abstrakt Horror. The site will likely be updated to reflect this soon.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R