I've tried Lync, I've tried Open Fire. Lync was so complicated to setup, I made a forum just to keep up with the notes. I got 4 people on it LOL, didn't even intend on it. One day while getting frustrated with Lync, I ran across an old Hak5 episode that was talking about Open Fire. I gave it a try and I was hooked.
Needless to say, I've added a board on my Lync server 2010 forum for alternative communication servers. Open Fire, and Spark are all I have listed. If anyone would like to post any helpful information, tips, tricks on there, I would really appreciate it.
Like I said, the forum is new, not really anyone on there, but If someone does come looking, I would like to help promote the Open Fire project.
I didn't even managed to setup Lync It's just a giant PITA, like it is often with MS products.. Though it has nice integration features with other MS products, but it is just too complex.
It took me 2 weeks to set up Lync for me. Very scarce documentation, the videos that were suppose to help you install it where misleading. They skipped about 5 critical steps in the videos and documentation. Microsoft never published what they did as prerequisites, before even attempting to install Lync.
I feel your pain hehe.