I've updated the Google Sketchup Template I use. I put the latest version dated 20 Nov 2011 in my collection on Google Warehouse (for anyone using the template). The new name is USPSA Stage Design Template under DVCMarkR collection.
The update adds a no-shoot between the top and bottom targets on a stacked target set...to prevent edge-hit scoring issues.
Also some new steel.
Didn't you just exchange one set of edge scoring hits for another set of edge scoring hits? Instead of getting a hit on an edge that scores points on two targets, now you'll get a hit on edge the scores points on one target, and and a penalty on the other one.
No more so than any no-shoot that overlaps a scoring target (see roughly half the approved classifiers). It does, however, avoid the opportunity for a lucky shooter to get 8 or 9 pts with one hit.