Trevor, I'm still working on those darned round things! I am down to 39 for the "master set" of E254 plus a few very minor lettering variations that I have noticed, I just found another the other day while looking through my dupes--but I am feeling more like a stamp collector with these at times because of how small the variations can be.
-Rhett
my wantlist:
http://www.starsofthediamond.com/wantlist.html
Edited to add: You can also see the variation in the 1907 Dietsche's based on the order of the text in the stamp area, the common one has the 3 lines of text first followed by the "Place stamp here" while the tougher one has the two lines "Place stamp here" first followed by the 3 lines of text (just another way to tell the variation).