For what it's worth, I wrote a script to find how many parts are affected and ran it on my parts directory (mostly six months or so out of date). Assuming the script to have no mistakes (always a possibility!) then of the 675 parts found with a ~moveto only 30 were affected.
Script (enclosed) looks for parts with a "~Moved to" containing any type 1 with non-standard matrix. It generates an LDR (enclosed, with slight positional improvements) with pairs of aligned parts (red=oldpart, green=newpart). Upgrading the LDR with MLCad 3.4 "breaks" the position of all the red upgraded parts, as shown in the jpegs (although not always clear from the 2D jpeg until you inspect it properly in 3D).
BEFORE UPGRADE:
AFTER UPGRADE:
Script (enclosed) looks for parts with a "~Moved to" containing any type 1 with non-standard matrix. It generates an LDR (enclosed, with slight positional improvements) with pairs of aligned parts (red=oldpart, green=newpart). Upgrading the LDR with MLCad 3.4 "breaks" the position of all the red upgraded parts, as shown in the jpegs (although not always clear from the 2D jpeg until you inspect it properly in 3D).
BEFORE UPGRADE:
AFTER UPGRADE: