There are valid reasons for leaving it any which way. Personally, I like to leave any cylinder with a load on it. Loading a cylinder keeps the seals pushed against the gland-rod, and against the piston-housing. By keeping the seals in shape, they last longer. Pressure in the cylinder also keep foreign matter out. This is a big reason you see so many manufacturers invert the FEL lift cylinders. With the rod pointing up, rain can drip down the frame, onto the rod, and get into the cylinder. With the cylinder inverted and pressurized, there is no chance of this happening. If you notice on most backhoes, any cylinders that aren't normally inverted are set so that when the machine is off, the rod is being pulled on. This keeps pressure on the rod seal and keeps junk out.