Thanks racinghamster. The problem is that the "rules" vary from person to person as much as the hamsters personalities I believe.
It was just a thought that maybe we could try to spot trends as I was asked, by a prospective new owner for my pups, if there were any stats that would indicate the chance of fall out if he got a pair. I had to say that I had no idea how many pairs or groups are together for life etc...so it got me wondering if there was anything we as a forum could do to get a better answer than..."it depends....." after all we must have quite a cross section of owners and experience on here.