Something to consider:
Right now, we are moving really quite fast with the push to get Darksend up and running in ts full glory. The X.X.X11.5 builds came out less than 24 hours ago, and the x.x.11.4 builds really only came out about 24 hours before that. Today is Saturday, and I am going to assume many people who work during the week will be able to sit down and read the many various threads on here and bitcointalk.
Personally, I think getting 60% compliance in 48 hours is pretty impressive, considering that although everyone has a stake in DRK, most of us have to make a living elsewhere. This was, in fact, the prime reason for the capability to "spork" when its needed rather than trying to hard fork at a particular time.
At some point the incentive to update needs to be enforced for pools and MNs. What is the incentive to run them? Well, to get additional DRK, of course. So if that stops happening, pool and MN owners will start trying to figure out what went wrong, and figure out that they need to upgrade.
In the meantime, many of the OPs in the developer threads still list x.x.11.4 as the current version. Can we get a single point of reference on here that matches bitcointalk? I like this board much better, but I had to go back to check the OP on bitcointalk to find out that we had a client upgrade.