I'm replying to the whole of comments on this article. The write amplification problem goes up as the number of "free" sectors/blocks goes down. Many solutions have been presented that don't allocate X% of the hard drive... but I'm not sure than any of them let the hard drive's SSD controller know they aren't allocated.

For that to happen, the OS has to have TRIM support, AND the block in question has to be on a volume that the OS is managing.

My worry is that if you have a blank partition, it's not being actively managed by anything, and thus isn't going to be TRIMed, and thus the SSD doesn't know the blocks are free for use.

Thus, leaving an unpartitioned area isn't going to help.