Good question. I'm not an expert on the MX series options/features, so forgive me if I am incorrect. Only briefly sat on my buddies MX5400. Perhaps things like:
- Cruise control
- Linked pedal
- Fender mounted loader joystick
- Standard rear remotes that aren't a $1500 option
- A loader that comes with a bucket, and a cutting edge, etc
- A seat with armrests
- Not having a treadle pedal
You got a good price for your MX, but when I build a basic MX5400 ROPS w/ loader on the kubota site, it comes to over 43 THOUSAND dollars.