I've got a lot of skepticism about this "new and improved" engine.
The engine is by no means "new." We know of certain potential improvements with some new bearing races inside the engine. But that has nothing to do with the water cooling and everything to do with continually dealing with deficiencies they'd created before. It's not "new" though.
It is, at its simplest, the same old engine with a bit of new plumbing going around the exhaust valves inside what is otherwise the same old heads. Nothing radical there. Yes, they changed some cam/timing/induction parameters. But that's all just tuning of the existing system rather than anything radically new.
Jerry touched on the real question. It's not some revolutionary engine that's a worry. The old engine has been worry enough. The question is Mother Harley's poor history with just about anything new; whether it be evolutionary, revolutionary or simply adopted and adapted from the auto industry.
So, yes, pay attention to line coupling systems borrowed from the automotive world that, perhaps, won't stand up to the higher vibration and more exposed environment on the motorcycle. Issues like that are the biggest worry right now for Harley and its new water cooling toys here.