Sachtler DV-8 is planty big for this camera in my opinion.
i am leaning toward towrd the DV-6 but I find the legs a little scimpy. The head is great.
Video 20 is overkill.
I recently purchased 3 dv4 tripods. Coming from a guy who has used gitzo tripods, the dv4 for its class is more than enough. It is sturdy and a lot lighter than the other models it is all you need for prosumer cameras such as an HVX ,of which I own 3, even with the extra attachments. Unless you plan on shooting hurricanes or tornados you should be fine with a DV4.