Well, I don't have a specific example - but I do know that everyone I spoke to who had SSSE3 compilation issues had just recently bought their machine (e.g. the very, very latest model).  If we leave the check for `extmodel` in for now I'm sure we'll find examples pretty quickly (or not) when people complain it won't compile.  Just seems a bit wrong to exclude all Haswell processors.  Thoughts?