The question is "Is 1.6 ready ??" the short answer is NO

1.6 will need six months or more before it is ready for production machine
still a few bugs to work out with asterisk -addons (mysql addons and MP3)

FreePBX 2.5 supports Asterisk 1.6. There is one known bug in the ARI that will be addressed. Also, FOP does not work on 1.6. Beyond that, as bugs are reported we will also look at them. So from a FreePBX perspective we will try to be responsive if there are issues uncovered on 1.6.

There are already several things that have been done in FreePBX when it detects you are running 1.6 to facilitate people using it. I can not speak on the readiness of Asterisk 1.6 but historically, a burn in period of about 6 months has been prudent as Bubba points out.

The only issues I had (did not care if FOP worked or not so I did not look at it) where already in the system and I found patchs for them

I have not played much but from I see Freepbx is working fine.

but it is not a stable system, it crashed once or twice in a 5 ~ 6 hour span of "testing"
I had the system calling itself and listening to IRV then default to conf w/MOH

I remove all the mp3 files and dump fresh new recordings in the correct format and sometimes MOH still craps out
but that is not Freepbx issue it is releated to the know bug in the mp3 format

My CDR does not record calls on the system but then again most calls are are built via .call files which do not show up anyway...