Before shutting down, I ran the Blackmagic Disk Speed Test. It ran a few times using the 5GB size selected.
I then shutdown and replaced the stock SSD with the new one I got from OWC (macsales.com). The drive is an Aura Pro 2 1 TB. The following is the results of the same test made a few hours after the new drive was restored from my Time Machine backup made just before shutting down. Definitely faster, and of course roughly 4 times the storage capacity.