Samba4 advice for production use

As a suffering admin of a Samba 3 domain, I am desperate to upgrade to Samba 4.

However until it is formally released, it just isn't worth the risk of upgrading. If it's for a couple of computers or home, then fine. If it's for an organisation that will lose money from computer downtime then don't do it - the risks are just too great.

To quote the official Samba FAQ:

Can I use Samba 4 on my production server right now?

No. Samba 4 is still under heavy development. Samba 4 is not due to replace Samba 3 soon. Many of the required core features are present, but the code is still alpha and user tools as well as some core features are still missing.

Edit (December 2012)

Since Samba 4 has been (finally!) officially released, I guess the answer has changed to probably yes - if you are not the early adopter type then you may want to wait until a few more people are using it, but the reasons I listed above are no longer relevant.

Now that it's 'stable', it's probably good to ask the question; aside from stability what issues are there compared to AD on Windows - see https://serverfault.com/questions/458424/samba-4-or-active-directory

The new Zentyal 3 (based on Ubuntu 12.04) is using Samba4 beta ( I don't think it has upgrade to the RC release of samba4 yet) and seems quite stable. They offer official paid support and claim that Canonical supports Zentyal 3 as well. http://www.zentyal.org/

I have done tests with it and am quite pleased. I haven't run into any show stoppers testing, but I also haven't had any suckers ask me to set it up on their network yet either. As always, your mileage may vary, but honestly, Samba4 seems quite stable right now.