Which may also explain their update cycle. They grew their business when software was distributed on physical disks and annual updates were normal. Personally, I don't find a most recent version of July 2012 alarming at all, but maybe that's just me. I do realize their user interface is somewhat dated, update cycles have become shorter and businesses have to adapt to stay competitive.
I can't speak particularly about DevonThink, but these short cycles are not to fix bugs but to introduce new features. How often are these new features really useful? How often do these changes disrupt workflow while learning new interfaces? How often do these changes introduce bugs?
Give me a stable program that's been around for years over somebody's beta code any day!