Does daisy chaining FireWire 800 and 400 cause all devices to use 400 speeds?

I recently purchased a Drobo, and in looking over some online documentation, I encountered [this support article](http://support.drobo.com/app/answers/detail/a_id/232/~/firewire-performance-and-stability%3A-mac) which states: > If a FireWire 400 device is also connected, it will pull down the overall performance to match FireWire 400 (FW400) instead of FireWire 800 speeds. I realize that if I attached a FireWire 800 device to a 400 device, and then that 400 device to my computer that obviously I'd only see 400 speeds from the 800 device, but this KB article seems to imply that connecting a 400 device to the other FW port on my Drobo, and having my Drobo connected via 800 to my Mac, will cause the Drobo to communicate at 400 speeds. Is this true? Is this a limitation of the FireWire protocol, a practical limitation common to many implementations of FireWire, or a limitation specific to the Drobo itself?