Today I realized my Astlinux WRAP box wasn't working anymore, so I decided to "go for it", and move all our IP phones (all three of them) to the new AskoziaPBX box. Only thing that isn't there for me is the ability to have all our phones ring on incoming calls, but that's not a big deal at the moment.
So far I'm REALLY impressed with Askozia. I'm also pleased with how well it works with the HP t5135.
Latest beta allows you to set a ring group.
Thanks Mat - I'll definitely check it out. I've just setup the m0n0dev environment so I can try to help.