My addled grey cells seem to recall that a while back there was a bit of a fuss because the FAA wanted to merge DC10 and MD11 licences - despite the aircraft having distinctly different handling characteristics..
For my pennyworth the MD11 never 'looked' right...appearing in take off configuration almost as if it were in landing mode, an awful lot of flap out..
I remember the first time I saw one when working for AA. It looked mishapen, parts put together rather than a complete design.
If it don't look right - then it don't fly right!