So I don't know the very specific details for NWN campaign speed on the pc. I understand it's a 10% increase, and in the future it might be include armor restrictions. I haven't seen anything about a weight restriction.
I did get a brief pdf of the 3.5 barbarian for speed.
Fast Movement (Ex): A barbarian’s land speed is faster than the norm for his race by +10 feet. This benefit applies only when he is wearing no armor, light armor, or medium armor and not carrying a heavy load. Apply this bonus before modifying the barbarian’s speed because of any load carried or armor worn.
Of course this is in a system where small races only have a movement of 20ft, instead of the medium creature movement of 30ft. So a hafling barbarian could move 30ft a 50% increase, while a human could move 40 about a 33% increase.
If the speed will remain at 10%, and the armor restriction will be put in... I'd be happy not getting the higher movement speed bonus as a trade off for not getting hit with a weight restriction, unless overloaded. I wonder if this has been brought up before, or if anyone else has an opinion on it.