Well, you probably already know the weak spots of both.. if not, the deere is at risk of eating a head gasket due to flex from the engine being part of the frame essentially...  and the case is full-time mfwd, so you can't turn it off when roading, etc. The circuit board for the powershift can be problematic, and hard to source and expensive if you do find one. I don't think the 504 will be an issue for you, the electronics will most likely be your culprit if you have any trouble there, and of course, if the powershift trans develops issues, it's going to cost a fortune and not a lot of experience out there that know how to work on them. That being said, I prefer that cab over the 8430 cab, visibility is 3x better, and the air flow in the cab should you have to use the windows is better in the case since the side window hinges at the rear, which funnels the air in towards you and out the back window. When the a/c is working though, I could always get my 8440 much colder than the case, but that was an airflow issue with the case. I think Elmer's still offers a high flow fan that might solve that. Lot of weight difference between the two, if you're doing something with heavy draft that was working the deere, you may struggle to get it done with the case due to traction.