I'm ONSSI certified and I really don't care for ONSSI, despite installing dozens of different locations. My company sold it because a few years back it was showing up on multiple bid specs. Onssi is not 100% user friendly. Views have to be defined in an administration program which interfaces to a milestone recorder. The software requires a ton of back end power to run, and your client PC's better exceed their recommended specifications. It does have some nice features and once you get it set up and configured properly its good, but getting there is a challenge in itself.
LS/ES is a decent recording end, you have some nice features, the fact that failover is built into the software is cool, but you need a spare recorder sitting their waiting for another recorder fail, or freeze up (which happens).
But like John said, what do you plan on doing with it, and I'm sure the group can figure out a better platform.
Are you primarily interested in usability or feature sets or? If you can clarify a little, we can provide better feedback.