If you want to use both ports to hook up printers, you have to use a customized firmware because stock firmware don't allow using both ports at the same time.
I use 1.9.7.3c from oleg, and that one works fine in my setting. Have a browse in the firmware area of this forum, and have a read about all different versions and what characteristics the different version have.
It is not possible to say this version is the most stable, because it depends on what kind of internet connection you have and what hardware you use with it.