Just for the perspective:

Sun Solaris only supports (and has only ever supported iirc) one system
with two different CPU clockspeeds: the Blade 1000. I'm willing to stand
corrected, but to convince me you'll have to provide a Sun document.

Sun's use of 'supported' and 'not supported' are very similar to Perry's,
and people actually pay them..

Even across domains in an E10K Sun's preference is to have CPUs of
the same speed and cache size. I have seen a mixed cache domain run,
but Sun specifically declared it to be outside support until the CPUs
were replaced.

They do support different steppings together, except where explicitly
verboten.

Quite simply, the combinatorial explosion of testing of concurrently
available products has to be constrained all along the line for time
and cost. The high minded principle of 'the system must be perfect in
all conditions' has to be predicated upon such constraints.

I don't think NetBSD should be any different from the other OS's in
placing a ring-fence around 'supported' and 'may work, but not supported'.

Particularly given NetBSD works across more platforms than you can shake
a stick at already!

-- 
-Mark                   ... an Englishman in London ...