I'd be careful with pure research languages like ocaml. It has some advanced features (polymorphic variants, functors, camlp4, etc. ) that even smart people have a hard time understanding, because they are probably the subject of someone's phd thesis. Also, LFSP's can be quirky: in Ocaml, for instance, native integers are only 31 bits (using 32 bits requires the Int32 module, which requires its own set of operations to use. Don't you love static type checking?)
Bugs in LFSP compilers probably appear much more often compared to LFM compilers.
Do we admit that smart people aren't infinitely smart? With LFSPs, I often get the feeling I'm too stupid for a language, but in many ways it's better than often feeling the language is too stupid for me.
Who cares whether you got 31 or 32 bits? The different operator names are because Ocaml doesn't have operator overloading. For statically type-checked and "overloaded" operators and functions, see type classes in Haskell.
Bugs in LFSP compilers probably appear much more often compared to LFM compilers.