I've just come upon an interesting paper that experimentally compares the performance of OLSR, BATMAN and Babel.
Real-world Performance of Current Proactive Multi-hop Mesh Protocols. M. Abolhasan, B. Hagelstein, J. C.-P. Wang.
http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1747&context=infopapers
Short summary: see Table II on the last page.
A few comments on the paper:
1. Section II (the informal description of the protocols) doesn't make much sense. Ignore it.
2. They evaluated original OLSR, not OLSR-ETX as used by our friends in Vienna and Berlin.
3. The results in Figure 3 would appear to imply that there's a bug in Babel -- it loses a packet every time it switches routes. I think I understand why.
4. They ran the routing daemons with the default parameters. This means that BATMAN ran with an OGM interval of 1 second, while Babel used a Hello interval of 4 seconds. It would have been interesting to see the results with similar parameters.
5. They didn't measure the amount of routing protocol traffic.
Juliusz