I was able to get my WoW dirctory down to under 17GB on my SSD. Aside from the usual /cache /updates and patch files I went into /data and there was a /data/cache folder as well with about 4.8GB of stuff. I renamed the folder and launched WoW - it recreated the /data/cache folder, but it's only a few hundred MB now, not 4.8GB. I'm not totally convinced this is a safe thing to yet, I'll let you know if I find any problems. Every other post I've seen (including some from blues) say that it should take about 22GB total once patched for 4.01