5 years and counting with no oil cooler in South Florida heat. The benefits are negligible. Getting rid of the catalytic converter will cool your bike immensely. Adding a FuelMoto tuner will give your bike a huge boost in performance and cooling.
You're not going to have any heating issues. Plenty of bikes out there without the oil cooler, running in extreme temperatures. Indian even stopped including them on their bikes as a stock item. I think I remember hearing the motors were running too cool and had problems getting up to temperature or they just wanted to keep production costs/final price lower on their bikes. Whatever the real reason.