I\'m looking for suggestions on Flash realtime servers. Currently, we use a combination of Moock\'s Unity and Red5, but there are a couple problems. First, we are moving to AS3,
For future reference, we ended up going with Wowza. Wowza and ElectroServer seemed pretty close in most aspects, so we tried to do a little demo in each one to compare. We had some trouble gettings started with ES, so we just went with Wowza.
I prefer red5 , it has been developed a lot these lasts months and i found it pretty stable. Once you get one app working the rest is easy and all the requirements you mention are available. If for "more stable" you mean the red5 source code changes too much , yes it does if you use the svn but you could choose one of the old versions and have a pretty good server for a while until you need to move to a newer version.
Also there is nothing like open source , you can change anything and share it so others can help improve it taking something and giving as well, the problem with a commercial solution is that even when you get proffesional support or a pretty stable product you will get the answer "we dont support customized servers" or such when you have very specific requirements, so forget about experimenting :P
Give Wowza a try! I've only used it for webcam recording, but the experience was very seamless, a far cry from Red5. Plus as a developer you can use the full Wowza for free AFAIK, so you don't have to take my word for it. It's easy to install, they have good code samples, it really gave me a good impression.
Another interesting fact is that Wowza is made by ex-Adobe/Macromedia engineers who used to work on FMS.
I vote ElectroServer - it's pretty stable, reasonably priced and I've met the guy who runs the company and he's a swell guy!