One of the problems I have with flash thumb drives is that when you've been using them for a while, all the memory cells become "dirty". When that happens, writes to the drive become slow as molasses as the drive is forced to do reset-empty-cell-then-copy operations on every memory cell you write to. Since SSDs are also based on flash, do they also have this problem?
I have a late 2010 iMac, and sometimes it spontaneously wakes up, usually within a minute or two of being put to sleep. Other times it spontaneously wakes up during the night. I can tell because if it's waking up from a true sleep, the wifi connection takes a few seconds to start up, but when it's just a blackened screen the wifi is instantly available.