I just ran the launch all apps test. All apps (around 80 were launched) taken around 30 seconds to launch from the HDD. I then closed them all. Now that they are all cached in the RAM, I opened them all up again and they taken around 6-7 seconds to launch. It was like watching them all open on an SSD! This is the benefits of App Cache that you would not have experienced back in 2009. I'm not saying that people should go all HDD no matter what, I just saying the HDD's are still great.
Yep, make use of the caching in Mavericks and use sleep and the boot and launch times are irrelevant.