>Of course. My question is whether if you had two programmers of average skill write the same thing in MUMPS and, say, Java or Perl, would the MUMPS version really be that much less maintainable?
MUMPS version will almost certainly be more unmaintainable (except when you use Perl). MUMPS is not much different from COBOL in that regard. Except when it IS different - there's a 'wonderful' feature called 'abbreviated code' which allows to write code as if it's a line noise.
The only powerful feature in MUMPS is built-in multidimensional arrays. But right now it's more than matched by NoSQL and SQL databases.