I have no experience with any of the other brands other than the Sony, but I will say that I am very impressed with the Sony RM-BR300. It provides control of all features to the EVI-70 cameras. I have no idea how much the other brands can control, but with the Sony, you'll have control of all of the D70's features (and other cameras in Sony's line up) such as: power, shutter, iris, brightness, memory presets, automatic exposure, backlight, zoom, white balance, digital zoom, focus, pan, tilt, Red/Blue gain, menu menu display, etc.
When using more than one camera, I have found it very convenient to adjust each camera's white balance, color, iris, focus, etc. for fine control or so all cameras all match.
It is entirely possible the other brands have most or all of these features but I feel there is an advantage working with the same brand for compatibility and access to all features possible.
Just my thoughts...