Here is a comment from the NI forums regarding source code control for LabVIEW:
When I started mentoring a few years ago, the team did source control by periodicly copying and renaming the entire directory. That worked for backup, but misses the major advantages of source control (history tracking and simultaneous work). We set up CVS and now everyone is comfortable with source control, which I think will greatly benefit them in their careers (I meet many people at work who only use source control because they have to, and are missing the great benefits).
This year, we still used CVS with LabVIEW, but it felt like we were back in the old days of only creating backups. Without graphical compares, it was very hard to reconstruct the history. Without merging, we couldn't work on the same file at once. We tried to mitigate that by making small files, but that didn't always work out. It also seemed like many times, changing one file affected many others, and I never did figure that out completely. In speaking with my manager at work, he also complained that it was very hard to use source control with LabVIEW. If we can teach everyone now how to effectively use source control with LabVIEW, it may help the adoption of LabVIEW in industry, as some of the misconceptions get broken down.
Is this the experience of other teams? If source control is really not workable, I think my team will have no choice but to use text programming, no matter how wonderful LabVIEW is.