I had a 743 with over 6,000 hours. It was just fine. The engine was hard to start, but when running, it would go all day.
With propper care, i heard from a bobcat mechanic the pumps/motors will easily do 10,000+ hours. There is a member in here that has, i think, over 12,000 on his 743. Its on its third engine, but the hydraulics are still original. The pump is getting a little lazy now, but a few hundred dollars, and it will be back to how it used to be.
The lower the hours, generally the less pin/bushing wear too, but this goes on the operator, if you don't grease it, they will be stuffed real fast. I have a 753G with just over 1,000 hours. The lower pins on the bobtach are totally stuffed, so bad that the bosses need replacing. It has 1,000 hours on it! if you don't service the machine, it will wear, and fast.