I vote to leave it on.
The Mikuni oil pumps almost never fail. On a Seadoo, what normally happens is that the little hoses from the pump to the manifold get brittle (or some times gooy) and they break. OR... the little nipples in the manifold plug up from the heat cooking the oil. (this takes years of neglect) When this happens the owner complains about how bad the oil system is... when in fact, they never serviced the system!!!
Every year... or at least every other year, I recommend changing the small oil lines, the filter, and cleaning out the nipples, and checkvalves. (poke thought the nipples with a small allen wench, and use carb cleaner in the check valves) Then, when you bleed the system, you will have a visual reassurance that it is pumping.
The only skis I remove the oil injection from is in a Yamaha. Anything bigger than the 701 engine can use a little extra oil to stay healthy.