I can't edit my stacks at all - going through all the motions and then clicking on Save gives me the old "Problem occurred while processing submission" error. I have 266 + 5 (from what I have read so far in this thread and my mind still boggles about this enlightened way of counting) games in my Collection stack and about the same on my wish list. This was one of the main reasons for using GS to keep track of my collection. The old system actually worked just fine so if it wasn't broken, why fix it?
Anyway, I am all for change if it's for the better. Not sure in this case though. After being a member of GS since 2002, i.e., almost 12 years, it's a pity that I am going to be forced to look elsewhere for this functionality if GS don't get this problem sorted soon.