I have a HL-2170W and miss the duplex the 3 times a year I use it. I was mostly letting people know that they more or less still make the same printer (at least, as far as I know the new ones have not become crap).
The HL-L2340DW comes with a starter toner cartridge that is good for 700 pages, so it is not a terrible way to have convenient printing for a decade.