I understand the perspective from both sides here. However, in previous experiences with non-mainstream developers, usually it's like, "If you purchased the product after 04/01/2009, you are entitled to a free upgrade."
I understand this can be a loss of revenue for you guys, but at the same time, there are people like me out there that two weeks after buying the product find out there is a new version about to be released and has no free upgrade path. When I first heard (during my installtion) about the Beta, I was excited to see the new features and improvements that have been in development for so long. However, I would have waited to move forward with my purchase would I have known there was a cost involved.
I think that moving forward having a posted and updated Product roadmap will help customers avoid these problem; however, I think Open-E corporate should consider coming to terms with current customers that purchased during a defined time-frame. At least maybe offer a discounted rate of upgrade.