Just buying a new camera (Canon G16)

This can take SDHC or SDXC UHS-1 ...... from my look at specs .. max write speed would be when using 1920 x 1080 60fps video

Canon state this as being 32GB for 121min of video ........ quick division shows that this equates to 3.2Mb/s
So does this mean that I might as well buy Sandisk Extreme SDHC cards ....... these are 45 mb/s , and there is nothing but extra cost (no benefit) to buying Sandisk Extreme Pro 90Mb/s cards.

Both are Class 10 UHS-1 cards