In my opinion, oil cooler is a good thing, have temp guages on the Harleys, and it's measurable, they do keep your oil cooler (stabilizes viscosity).
Suggest installing the thermostat on the oil filter mount, Jagg makes 'em (I think). Was first order of bidness for Primary Spousal Unit's CVO Dyna.
But as was said previously, keep that puppy moving. Closest I've ever come to overheating the Dog was during parade last July 4th. I have the BDM cooler that matches stash tube. That day I was wishing that I had two coolers, but reading some of Donny Smith's stuff, that may not be a good idea...