Similar experience here with the same 900CRM engines. The port oil cooler went at about 400 hours and the starboard went about 20 hours later.
The issue on my boat is that the port (1st to go) was a 3 hour, 1 man job. The starboard, because it is outboard with very little clearance took 2 men almost 8 hours to complete.
If starboard had gone first, I definitely would have done the easier port one proactively.