Well....the speed limit us like 5 mph...and going any faster just results in waiting for a bridge and lock.............
It might be 6 but that's not a big difference. We have never hit anything in our three times transiting the canal.
The Virginia Cut has some unprotected water and additional drawbridges that are not "on demand". Elizabeth City is a nicer stop than Coinjock (I think) and it's free.