I'd be glad to share our experience.
So far, I have had very little problems with eGate. Our live and test machines has been running over a year. We have eGate 4.5.1 loaded in AIX 4.3.3 running on an IBM pSeries 660 with a two-way 450 cpu, 1 gb of RAM, and 36 gb of external raid 5 disks (plus the mirrored internal os drives). The only problem we have is a memory leak which causes the paging space to grow and never clean up. There may be an fix, but I haven't looked in a while. About once every 6 months, I stop and restart eGate. It drops the paging space to about 4-5%.
I would like to see more supported OS's. I have a post here for a linux question. I can't believe they still only support Red Hat linux 6.2.
Other than that, it runs like a champ. Also, once you get used to it, it's very easy to manage.
I wish they would bring back some features from the 3.6 gui. I liked clicking on the component and seeing the messages flow. Now I have to tail -f the logs.
I hope that helps.
Good luck deciding.
Mark Kozusnik
Wheeling Hospital