UM doesnt have a problem and nor do I with minority interest greek orgs. All the orgs. try to go to everyones different events. Like NPC/NIC's will go to NPHC's step offs, NPHC's will participate in or come and watch Greek Week, etc. Evereyone invites everyone. Not saying there is 100% harmony, but its pretty close.
However, I did have an alum once say to me that she really didnt see a need for multicultural GLO's b/c she felt that it was making NPC/NIC and NPHC orgs look bad by insinuating that they arent trying to integrate or be diverse. However, I almost joined a MCGLO, so I just blew it off and tried to make her understand thats not what they are about.