OK, so the reason you are interested in this is for the ability to write, share and use patches that can be used by those who pay for a license to the code, to be able to add features without having to rely/wait for the vendor to do so?
Yes, while it is certainly worse than full Free Software from a community perspective, it is still much better than closed source commercial software since you are at least in control - even if the developer shuts down or abandons the project, you are still able to fix bugs and improve the program (you or anyone else who decides to distribute patches - assuming the license doesn't explicitly forbid that, but it'd be pointless to do that IMO, not that some didn't try it). And if you ever decide to move somewhere else, you can still get your data out of the program (modify it to dump to another format or just use the code to make your own converter) so you're not locked in either.
