Though I fully agree with the comments about the quality of the software provided and also the fact that if all source code is provided you can maintain something yourself if you need to, I feel you have raised key point here.
To be a open source / free LabVIEW product that gets a Gold or Silver Product recommendation by NI, the Product or community behind it must still be active and vibrant.
As said previously the Open Source tools that work all have healthy & active communities behind them look at Bugzilla, Subversion, Python and many more.
Without that active & vibrant community behind the tools, they will die off leaving you in a dead end situation when they no longer work with newer version of OS or LabVIEW. Some new user of LabVIEW may never even really get to grips with the tools and use them with some level of support & help.
I think the LAVA CR tools & JKI free tools are all example of good and active communities. I regretfully for this reason have concerns regarding the OpenG tools.
I am a keen user of the OpenG tools, I have taken part in the OpenG forums and even once posted a possible fix for a tool that no longer works for LabVIEW 8.2.1 or newer. So with apologies to Ton and other who I know have and do work hard on OpenG I must say that to me it no longer fit this criteria. Looking at the OpenG forums there is very little activity and has been for a long time now. In fact the most recent posts are all spam one. As I said this is a personal option, but as LAVA CR's grow & the NI community grow OpenG feel to be faltering.
Dannyt