Hallo!
i think all of the iem_matrix objects are covered by iemmatrix.
basically all objects in iem_matrix are specialized versions of [mtx_*~]. however, i believe that [mtx_*~] is now so optimized, that you will not gain anything from using the specialized versions, but you lose a lot of flexibility.
Yes, I'm aware of that - the only problem is, as already said, backward compatibility ...
Thomas Musil used the iem_matrix a lot and if you want to use some of his patches you will need iem_matrix ! However, I will try if it's easy to make some wrapper ...
LG Georg