I’m one of those late-adopters, who lets a few versions go by before getting into the water. Especially with something as important to me as Devonthink Pro.
So, I am still using v.1, not the public beta of v. 2.
I rec’d an email kindly telling me that
As you have purchased within the grace period you are eligible for a free upgrade to version 2.x. Please find here a new license code for DEVONthink Pro Office 2.x:
Will this expire if I wait too long? I may even wait for the full (not beta) release.
No, you are a registered user of DT Pro 2.x also. You already hold the license code for it. 
If curiosity gets the better of your resolve to hold out for a while, see < viewtopic.php?f=18&t=7117> for tips on how to safely install both versions of DT Pro in your Applications folder.
Comments: Once in a while I have to revert to version 1.5.4 for Support purposes. I get back to version 2 as quickly as possible to get my work done, as the advantages of rock solid databases that can be open concurrently, with very fast and powerful searching and lots of other features creates a work environment that I don’t want to give up even for a short time. If you try DT Pro 2, I think you will also be hooked.
Thanks, Bill. Your endorsement of the public beta will bring me into the fold!