1) Adobe Systems has performed tests comparing LaserWriter IINTX and
LaserJet Plus. Their finding is that a LaserWriter IINTX in LaserJet
Plus emulation mode is generally faster than a LaserJet Plus, and is
more than 95% compatible. The newer ROMs in the LaserWriter IINTX will
increase compatibility even more.
The LaserWriter IINTX in LaserJet emulation does not fully support
LaserJet bitmapped fonts, but does support PostScript fonts. This may
explain your problems with the "jagged" output, if you're using
LaserJet bitmapped fonts.
2) The minimum number of "switches" is 100,000, if all performed via
software. We don't have the number for the DIP switches, as there are
too many variables to take into account.