I'm using currently CMake for something else I'm working on, and for this it does fine - although that's a much more basic project.
I am still not convinced that CMake can do what autotools does in the same 'autonomous' way. While CMake does obviously allow settings for all the configurable options, having the user set these manually kind of negates the idea of a configure step.
I also think that CMake does not allow for cross compilation - which is something I just added some rudimentary support for in the autotools build.
And now the clincher... None of what I have said above may be true - it's possible that CMake can do
all that autotools can do - but the issue is that I do not know how to make it do it, whereas I can make autotools jump through hoops while doing a double-twist

So even if CMake is the best tool in the world, the fact that I (and presumably the other devs too) have little experience with it would be a major obstacle. Tools should make life easier; not harder. There would be no benefit in CMake if we need to go off on some three hour vision quest each time we need to discover how to make the thing do what we need.
This is all just my opinion of course - though I would be prepared to exert some 'leverage', shall we say, if I felt it was needed.