I have WoW on my SSD (Micron S400v 64GB) and the lifetime after 1 year is downed to 99%, so thats 99 more years to go before it will fail.
And before i even put WoW on it i had Windows installed on it for over a year, now i have 2 SSD and Windows on my Samsung 830.
You can check this with Crystaldiskinfo or hdtune.
Old SSDs had the problem to wear down very fast, but the newer ones dont > atleast not the coming 100 years
So just copy/paste your WoW folder to the SSD, then make a new link from Launcher.exe to your desktop or where ever u like.
The only inprovement you get is faster loading times when phasing into zones (faster loading screen), further no difference.