... although I was disappointed recently by my usual go-to of the Brother brand. Their Linux/CUPS drivers are some sort of bizarre concoction of Perl scripts and x32 binaries... and still cannot print in duplex :/.
(I believe the duplex problem is probably a typo somewhere in the PPD or Perl script, but I don't know enough about PPDs and/or Perl scripts to be sure. I do know programming, hence my suspicion.)
Lesson is: Research if the EXACT printer you're purchasing is supported by the usual Gutenprint or whatever.