Several years ago there was a run in this area for the JD 346 ... I think the Jimmy Carter years and alot of peanut hay was baled. Those are tough balers and I can't say much for parts availability, cause I just have not needed any (knock on wood) The JD website shows them with a great breakdown and parts list. This particular model had the auto oiler and was disabled before I got it. Don't know why it was, has no effect on the performance.
Everything is pretty much the same with the exception of the knotters these are actually what I call ... twisters... that wrap the wire instead of a knot.
Wire does cost more. About 2X's as much ... Folks round here will pay an extra dollar a bale for wire, therfore the extra cost washes out. And the old wire from the bales is always hanging around for fence repairs!!!
I knew nothing about wire balers. In fact all I ever used was twine. When I decided to start square bales and talked to the old boys around here all I heard was wire wire wire and very few twine balers available.
As I said earlier, any baler has a comfort zone and once that is found it will eat up the hay and crap out the square bales.