About V3, well the first thing that came up is that I could recommend Sail to "experts" that do not want to work with smeserver because "they're so good at Linux". Yeah, those ones. Your port on Centos is a good move, although I am still using it on smeserver. Can't keep a heart from loving, as we say around here!!!
I still have to try DiSA and callback but it went very smoothly following your installation instructions. I'm not confortable at all with the process of migrating from V2 to V3. Too much of a blackbox for me when it comes to upgrade a production PBX. I wish I could import a working conf file from V2 (or V3 for that matter) into my new PBX.
The "Asterisk files edit" needs too much scrolling. Just to change the language, there is more scrolling than typing. That would be nice to have just one field in the "Global settings" where to set language.
So my first impression is quite good. The interface is neet. Great job!
Sophie