Do those moving parts ever cause any problems?Depends on the combine, our JD Hill master was always pitched slightly on even our flattest fields and the weight difference was unnoticeable really. I can't think of any real disadvantages apart from more moving parts?
The level land jD T series has a 10,000 litre tank vs hillmaster equivalent which has an 8000l That may or may not help with your harvest logistics .
The cab height will be lower on the road on a hillmaster when lowered , as well as the smaller tank you may well be limited to A bit narrower tyres compared to the widest approved option on a fixed axle machine.
One advantage to Hillmaster/Montana type combines is that they can be quite handy for getting g through gateways without taking the header off. You can often just pick up over the hedge or tilt your way through.
We are looking to buy a used combine, there are a few hill side models available locally, are there any disadvantages to running them on level land?