thanks for all the suggestions.
I haven't had much trouble with sisal and mice/rot. I'll stick with that. The only reason I asked about the poly is somebody I know swore up and down that it'd be better in that baler.
Didn't make sense to me since - as Leroy said - it wasn't even invented when that baler was designed.
-also had to laugh at the belt comment - my wife agrees, she just used some as a belt baling last season (where she made the comment "you know you're a redneck when you hold your pants up with baler twine")
I will look around for 7200 - the only thing I've seen around here is the 9000. To be honest, I thought that's all they made!
Must be nice out in those rural areas where people know what baler twine IS, and even give you choices.