As displayed in above screen shots, the single Azure Standard Storage VHD gives you (as promised) about 500 IOPS. Striping eight (8) of those, will roughly give you eight (8) times the IOPS, but not same magnitude of [MB/s] apparently. Still, the setup is better off, after, rather than before!
Do mind, that there are three levels of storage performance; P10, P20 and P30. For more information, read this.
I did this recently and can confirm that there’s a huge difference between using one virtual disk versus even three or four, and Windows Storage Spaces makes it easy to expose them as one combined mount point.