I am wondering if this is normal but I have noticed how I have to add quite a large amount of contrast and especially saturation in post to the clips off my XF300. I have changed nothing significant from the default settings so I would have though it would produce more realistic clips straight out of the camera. Anyone else getting this?

See this as an example of what I mean XF300 Very short test on Vimeo

EDIT - This one shows it even more. It was rendered in SD not HD so don't pay too much attention to the sharpness. Trains - Canon XF300 test on Vimeo

Try using Cine 1 Gamma and bring your color saturation to around #20 outdoors in the Color Matrix menu. See if this helps. It should crush the blacks somewhat and the color gain should bring out the colors somewhat more vivid.

As an XHA1 user, i can tell you definately, that their cameras shoot flat out of the box..
And as far as tweaking the in camera settings, i would rather do it in post anyways. Usually an S-curve on the RGB.
As suggested, go to the levels, and lower the blacks, raise the highlights, and drop the gamma just a touch..
For outdoor shooting, i like to drop the blues. It brings out the green in the leaves..

What framerate were you shooting with? Perhaps shooting in 24FPS yields the look your expecting??