The Aikido-L listserv folks have (I believe) had two seminars where everyone on the list -- from widely disparate styles -- were invited.
I went to the second seminar, which was held in the Virginia suburbs of DC, and it was great. The seminar was structred so that one teacher from each style represented had a 2-hour class. There were (if memory serves me correctly), sensei from the Ki Society, Yoshinkan, Aikikai, ASU, and some offshoot of jujitsu/aikijujitsu. The theme was "celebrate our similarities", not differences, and everyone had a great time. Needless to say, I learned a lot.
So, it CAN work.