though the fact that they've added the darknet mode suggests that that they aren't 100% confident about that!
That is completely and utterly wrong. The darknet mode was added to prevent harvesting of nodes simply by joining the network. In 0.5 (and in 0.7 with activated opennet) you can create a list of all Freenet nodes just by waiting. Nodes that do not have opennet activated are not found by this method (unless you are directly connected to them in which case you wouldnâ(TM)t need to search for them). That is the reason for darknet.