In April of 2015, my mother and I both went to our John Deere dealer and we each purchased a new X300. Hers is a 42-inch and mine a 46-inch. Otherwise, they are the same mower.
We have both had problems. At 212 hours, the engine locked up on mine. It was still under warranty, so the dealer picked it up, and fortunately, it wasn't the engine. The electric power take-off had locked up, causing the engine to lock up. It was $100 for the pickup and delivery, out of my pocket.
My mother's X300 has about 600 hours on it now, so it's out of warranty. So far, the steering has messed up, which cost her out of pocket to have fixed. Once that was fixed, she was mowing along one day, and the transmission started making a hellacious noise. She called her repair guy again. It wouldn't even drive itself onto his trailer. They had to push it onto the trailer. That ended up being a worn spline, failed pulley, and another $160 repair.
There's a reason you spend this much money on a mower.
It's supposed to last for years. Between mine and my mother's X300's, it's looking like John Deere isn't what it used to be. The Kawasaki engines are the reason that I've bought John Deere mowers and used them for many years. I'm not impressed. I'm to the point that I'm considering selling mine, which only has 216 hours on it, before something else happens.
I've praised the reliability and durability of John Deere mowers for many years. I am so disheartened over these last two purchases.