I have this dilemma. I've been working with making bigger panoramas. My Mac Pro is choking with 24GB of RAM and I thinking of going to 48GB. Then my 128GB SSD dedicated to scratch is out of space because it's been filled. Then things just break. I'm not sure if I want to upgrade to 48GB since it might not be enough. Then the next step would be 96GB, but that's over $1200 right now. I don't really use my Mac Pro much anymore (since I'm on the move quite often) and I'm not really sure I want to dedicate more money into it being 3 years old. My alternative is to get perhaps a 256GB or 512GB SSD for scratch. The advantages here is it's a lot cheaper and quite a bit more space. The disadvantage is it's a lot slower than RAM. What are people's thoughts on this?