Hmm. I don't have a Stacinator, so I can't say definitively. I love my SP wool -- have three covers -- but they are a full-cut cover. My boy is a chunk. Maybe you'd want something a little trimmer fitting? I like the trim fit of my Phunkymama cover.
OH if it were me, I would wait for sugarpeas, she has some really cute colors coming out. Not sure though how easy it will be to get a hold of one. If you can get a custom spot seventh heaven babies has some awsome wool sidesnapping covers. <a href="http://www.7thheavenbabies.wahmart.com/" target="_blank">http://www.7thheavenbabies.wahmart.com/</a> <span style="font-size:xx-small;">she has a wool cover in stock too.</span>