SSD is incredibly worth it for Aperture and video or music editing.  If you’re just listening to your music and just watching your videos, then they will not benefit.

You may want to check out what Raid levels do before deciding.  Striped is twice as fast and twice as likely to fail (2 drives treated as a single volume)  If one fails you loose all your work.  Striped also requires a fast bus speed, because if you aren’t delivering the data fast enough, then there is no benefit and only increased risk.  You need to look at how fast your computer can deliver to the drives and how fast the drives are capable of writing.  The drive controller may or may not be able to handle striping (but the MacOS can).

USB3 (5Gbps) cannot saturate a 6Gbps SSD drive at write speed … thus striping 2 drives will not improve anything at all.  Thunderbolt is capable of sending 10Gbps to peripherals, so there would be an advantage and unlike USB it doesn’t slow down.  Thunderbolt2 can write at 20Gbps.  With Thunderbolt you may already be using the bus for other stuff, like your monitor, so this will reduce the theoretical speed by that amount.