Ball Head for 400mm Canon Lens (1 Viewer)

Dears friends,
>
> I'm have to improve my support equipment which I use with a lens Canon
> 400mm with or not extenders Canon 2x and 1.4X.
> I use this equipment very much in rain forests which have very dense
> vegetation.
> I thinking to buy a ball head to use with the lens and extenders I' ve
> mentioned . I'm trying to decide between three ball heads :
> Acratech ,
> Gitzo 1378
> Bogen 468 MG ( Magnesium hydrostatic ball head)
> Could someone of bird forum give me a orientation?
> Thank you in advance
>

Not much use of ball heads in Bird Forum. I use a Markins ballhead with my spotting scope but it may be a bit pricey for you. Excellent results though.