http://www.computerworld.com/article/2929768/data-storage-solutions/average-cost-of-a-128gb-ssd-is-now-50-for-pc-makers.html
My SSD dramatically improved my Logos experience. [Y]
I upgraded to a 512Gb Samsung 850 PRO for performance reasons, thinking I'd get a significant boost.
I did get a performance boost of about 20%, but I'll confess to being a little disappointed. If you're already running a Seagate Momentus hybrid drive, it turns out that this is about the right increase in performance, based on Seagate's benchmark against a comparable SSD manufacturer.
If I'd known the performance bump was that small, I might have chosen to save the money.
As always, YMMV.
I went from a mechanical drive, to having a small cache drive, to having a large ish ssd (256gb - definitely not huge, but it was big at the time). For me the difference was night and day. So much so that I went out and bought another one and put it in my Laptop.