I am happy with my Macbook Pro 2009 and now Mojave and APFS (before HS and HFS+).
The only thing which is different - since a few days working with Mojave - is that the startup time compared to HS is significant longer - i think at least 30% longer. I am using same Apps as startup like Tuxera NTFS, Adblocker, Little Snitch. If the system is running i cant say if it is also slower or not - maybe the startup of Apps like word or Finder actions is a bit slower than using HS.
Perhaps RAM consumption of the OS itself compared to HS can be little higher and the 8GB system has less RAM free (for file action caching)? Or can be APFS general slower than HFS+?
Here Memory footprint direct after startup: I disabled NTFS Tuxera & Adblocker. Little Snitch is runing.
List is sorted by ram usage.
Looks like the 8 GB has only about 1,5 GB free.
View attachment 928966
Has someone an such startup foorptint of HS or El Capitan?
Is it really not possible to put in more RAM nto the MBP 5,3?