I'm still trying to determine how to answer your question. Normally when a question is asked "how can x help", the first half of the question describes the problem at hand. However, I'm not gleaning what problem is hinted at by "We have queue managers on Windows, AS400 and UNIX."
Could you elaborate further on what problems you see yourself having that deploying an MQ Appliance is hoped to be the solution to?
Cheers
Morag