MLton has been mostly unmaintained for 5+ years - GHC has a performance consortium improving it ( llvm, new code gen, new register allocator, parallel GC)... I'd expect it to be a tie now for sequential code.
http://mlton.org/cgi-bin/viewsvn.cgi/mlton/branches/llvm/#di...
but have no idea how functional (aargh! no not that functional) it is. There seems to be some activity on the trunk in the last 7~8 months, but possibly maintenance edits. Just putting it out there if anyone wants to poke. It would be sad for MLton to bit rot.