We’ve been using Cloverleaf (The integration engine formally known as QDXi 😉 ) v5.2 on RedHat AS 2.1 for the past 3 years or so. We run it on an IBM xSeries 345, and have been very happy with the rock-solid stability.
Since we are a client engine rather than the center of the universe, we don’t really tax the resources on our hardware. We had a planned reboot 182 days ago to update a raid driver.
The biggest selling points (beside price) in my book would be the ease of integrating Samba filesystem sharing to allow access to the filesystem using windows shares, and the ability to read files that Cloverleaf has open. My counterpart at the hospital has to cycle SMAT to look at the files (AIX) but I can look at them on the fly with a text utility without cycling. (and thru the Samba share as well!) I know that you can load Samba on AIX, but I don’t know if you can “read” those files while the process has them open for writing. I suspect not.