I did a basic test where I did continuous shooting and I filled the buffer on my Sony A6000. I timed how long it took for the camera to let me review an image. I don't know if this is a Sony limitation or if all cameras have the limit.
I don't normally shoot continuously and fill the buffer so I'm not sure how important this knowledge really is.
Below are the results. This might be handy if you need that buffer cleared sooner in order to take more shots.
Sandisk 16gb 80MB/s
Micro SDHC/adapter
UHS-1
RAW+JPG
21 images
22.5 seconds write
Samsung EVO 64gb 40+MB/s
Micro SDHC/adapter
RAW+JPG
21 images
31 seconds
Sandisk Class 4 8gb (speed not known)
SDHC
RAW+JPG
1 min 56 seconds