Used 7215 inline baler

There is a used NI 7215 for sale in my area. I currently run a NH 311 that I have rehabbed to generally reliable production, but I am/have always been intrigued by these units. I only bale 2000/year, but might do more in the future.
My 311 has some worn knotter parts my mechanic says might be hard to find when they go. That worries me a bit.
This unit advertised as having-new knives, new rails, I get the new knives but wonder about wearing out the rails?
My needs are unique. I bale short, young grass hay primarily for our training barn. I bale only to fit our operation and reliability is priority. I can fix about anything if I have all winter in shop to figure it out, but fast field repairs are not my strength.
I have new feed and pickup rebuilds, plunger assembly and knotter original.

Stay with 311 and deal with future knotter issues or go with newer inline?
Thanks

Used 7215 inline baler