Does longer firewire mean slower transfer speeds??
 

How long can a firewire cable go before I will start to see slowdown in the transfer of information?

I want to run some firewire that is about 100 feet long (if they even make it this long)...

I don't see any 100' firewire cables on B&H, but I did find this: http://www.bhphotovideo.com/c/produc..._to_6_pin.html.
You could also provide your own cables and buy the firewire repeaters individually: http://www.bhphotovideo.com/c/produc...eater_400.html.

I don't know the limitations of firewire, but the fact that B&H is providing a kit with three 66' cables and two repeaters seems to suggest that 66' is about as far as you can go reliably without needing a repeater.

Also, I may be wrong about this, but I think that an over-lengthy stretch will not slow down. What it will do is give you errors or just plain not work. Again, not 100% sure on that last bit of info.

EDIT: found this on good 'ol Wiki: