MXs were very good tractors and then they went downhill from there after they went to the MXMs and the Maxxums.  A former dealer mechanic who I trust very well and who has lots of experience with those tractors told me that if I ever bought a MXM he would quit talking to me and that we would be better off putting money into our 15,000 hour 5140 than "upgrading" to anything newer than an MX series in the Case IH lineup.  He said that they pretty well worked through the electrical problems the MXMs had early on but now they are seeing alot of mechanical problems and that they just aren't built as heavy as the old Maxxums were.