I like the looks of the hex head plug, but Putnam requires that the oil filler cap be safty wired. There're not many choices of where to run the wire to on the 919. I ended up drilling the head of the clutch cover bolt behind the lifter lever. That thing was harder than hen's teeth. But after it was done, I had a neat looking job.
I've never thought of the security aspect of it, but safty wire also serves as a seal. You'd easily be able to tell if your plug had been tampered with by looking at the safty wire. Razorbike's bud was lucky he had a locking gas cap or "Scumbag" would have dumped something in the tank.