The RAID controller probably presents the the drive as an array to the OS.
Wear leveling is an interal process which the drive determines where to write data. The issue you want to avoid is dirty pages. Without the Toolbox or TRIM, there are few options. There are 3rd party space conslidation and 0 write programs but results are mixed. The sure way is attach the drive to a standard controller and use the Toolbox.
The performance degradation depends greatly on your usage pattern. For a desktop using basic applications, it might be months. For a DB with constant I/O, it might be a days or weeks.