It's pretty necessary if you aren't moving between colocated boxes. "less than a couple hundred GB of data" is still a lot of data to be moving around, even on a 100Mb/s link, which almost no one in America has residentially, and isn't even a guarantee for colo'd machines.
In most cases, compression at the raw block level will result in HUGE size savings, especially since a lot of that may be free space. It might even make this transfer tenable.
