This was first posted as a comment under an article on lwn.net, but I thought it was important enough to post it here for others not reading lwn. Please go ahead and read the original article which is about the "Open Core" business model and its problems from the Free Software community point of view.
A commenter thought that syslog-ng was an example, which only exists as a marketing tool for the company's commercial offering. Anyway, here's my post:
First of all, I want to make it clear that I'm biased on the syslog-ng case, but still wanted to express my opinion here. I'm biased as I'm the primary author of syslog-ng.
I think syslog-ng is a completely different case from the one described by Neary. The GPL version is not crippleware, it was never published for marketing purposes only and for the majority of syslog-ng's existence only the Open Source stuff existed. The Premium Edition is only about 3 years old and syslog-ng started in 1998.
We never removed features from the OSE version, the Premium Edition only included _additional_ features, and a lot of those are already available in the OSE.
* TLS support (became available in 3.0, almost 2 years ago)
* SQL destination (became available in 2.1, 2.5 years ago)
* performance improvements (3.0)
In the other direction, we usually receive bugfixes and it is a pure technical reason that we used to require copyright assignment: I wanted to keep the two branches as close as possible (which if not done is the reason #1 why Open Core products become crippleware fast). _And_ since we heavily invested in automatic testing and our customers report bugs directly to us, we fix way more bugs in the OSE version than the community.
But anyway, I didn't think that the dual license model was so problematic at the time we made this decision 3 years ago. Our efforts have never been "Rotten to the Open Core". If you don't believe that, check out the git repository or read the mailing list archive and see it yourself.
And this whole mess is the past, OSE 3.2 has been relicensed, and it is true that we're going to publish non-free plugins, but anyone else is welcome to join and do the same.