Mind if I barge into your forum? I thought I might have some insight on the subject. If you want me to go away, please (politely!) say so!
At my undergrad campus we had Alpha Xi Delta and Alpha Gamma Delta. There was definitely no getting the two groups confused! Both groups had very distinct personalities.
Although I did have a good friend of mine comment one night that my letters on my bag looked like they said AXO instead of AXiD. Which was just weird. But he was weird.
Anyways, I could see how there might be more confusion since a Delta looks more like an Omicron then a Gamma looks like a Xi. But I just thought I'd throw in my $0.02.