as you might as well know for dump you should find the appropriate blocksize to get the most performance of copying data from on hdd to the other.
as for rsync from personal experience i can tell you that 70 GB of data took about 7 hours to copy through the network from one sata II hdd to another (computers were directly connected through a 100 MB ethernet link).
maybe this is helpful to make an ideea about the process.
all the best,
v
PS: just noticed this is your 1st post, welcome to the new community