I've never actually used SCons. I used Cons, which was the predecessor system. Cons was fairly slow, but not more so than autotools. CMake is quite fast.
> Simple things which are trivial with autotools (for example: "compile the
> same sources for four different platforms: one native and three cross" or
> "compile the some sources twice using different compilers to compare
> output") become serious problem and require a lot of kludges.
I don't see why cross-compilation would be any harder (or easier) on CMake versus autotools.
I think you are missing the point of my systemd vs. SysV init comparison. SysV init sucks. Everyone who is technically knowledgeable in this area admits this. But system administrators are very familiar with it. It is standardized in the Filesystem Hierarchy Standard.
You might argue that that standardization is a mirage, because every distribution uses it differently. In the same way, autotools standardization is a mirage because everyone uses a slightly different set of macros and generator programs. Some projects don't even use automake at all, but simply autoconf. Some projects have wrapper scripts, and some do not. Some projects check in certain generated files and others don't. And so, on as we discussed.
Like autotools, SysV wins in every way except the way that's actually important: actually being good! If you are going to recommend that people use an inferior build system because of compatibility and the difficulty of retraining, you should also recommend that they use SysV init, for the same reasons.
In fact, whenever systemd comes up in a discussion, you see a lot of posts by system administrators who are scared of the change-- and rightly so. They know that there will be a period when they will not be as familiar with the new system as the with old. They also know that the new system will have rough edges and possibly a regression or two. But guess what-- positive change can never happen when people refuse to learn something new.