Personally i use a sony pmc-m10 behing a field mixer (mini jack line in).
The Marantz PMD661MKII seems to fit the bill too (XLR line in).
I never understood the industrial choice behind the Zoom H4N inputs, and its a pain to explain to every h4n owner i meet the differences between mic, instr, and line input, and why in impedance hell sometimes it will record a mixer line out and sometimes it will be distorted no matter what. For that mere reason, i stay away from their entire line of products.
The family of portable recorders has greatly expanded those last three years, so you might need some time to think about your precise needs and use cases to make a choice. There is a whole Tascam lineof products that do 4 tracks under 500$.
My personnal buying "strategy" is to go for the under-200€ options, and/or save for some time and buy the over-1000/2000 € one. That's the leap i think one needs to take for a significantly better sounding product nowadays.
Just out of curiosity, what field mixer is it ? (that "strange XLR", wouldn't it be a Tüchel ?)
(ps. i just realized the pcm-m10 has been discontinued :(((( )