Does any one know if the HPX300 has electronic image rotation or "flip" for use with Cine Lens Adapters like JVC's 1/3" HZ-CA13U?

Yes, it does. In fact it not only rotates the image in the VF and LCD, but also records the image upright onto P2 as well, eliminating the need for flipped modules when using a 35mm or 16mm DOF adapter.

Awesome. Thanks. I couldn't find that info in the brochure.

No problem, in the manual its referred to as (reverse scan) I believe, so its a bit of a "secret power" the camera has. Its not really noted on the brochures but it does do it.