I have a 1996 D3C series 2 LGP machine, with a little over 4800 hrs on it. Never once has it gave me an issue. I'll I've done so far is changes the fluids, lube it up, and keep the filters clean. I guess I have replace a couple rollers, and a oil pressure sensor, but those are small little things that I wouldn't even count. Its been a great little machine. With that said, I'll probably be due for an undercarriage pretty soon. Don't know if at that point I should sell it, and step upto a D5.
Have you thought about a D5? Its only a couple thousand pounds heavier, and more hp.