It never hurts to have more information.  I had a bad seal in the RD-2C and was rapidly losing oil, but didn't know it until the oil pressure started dropping.  Luckily, I was still in the pattern and was able to land safely and without damaging my engine.  If I had initially installed the oil level sensor I would have had more time to handle the emergency.  So, I vote to keep it.  

Mark S.  

P.S.  I've since installed the low level oil sensor switch.  I also have a low coolant switch.