How has Apple set up the iMacs that have both a SSD and a HDD? The OS and apps are on the SSD, but where are the user folders located? On the SSD or the HDD?
I can't say for certain, but I would expect that they would go with the default, which is that the home directories are created in /Users, which is on your boot drive, which you're saying is the SSD.
I googled this question and got a link to a post on the discussions.apple.com forum saying a 2010 iMac purchaser found the /User folder on the SSD.
It can be moved to the HDD by drag and dropping the user folder there and then in System preferences->Accounts right clicking on your account name to bring up Advanced Options. This lets you edit the Home directory to where you copied it. Then you have to restart the computer.
But isn't it better to leave your home user folder on the SSD because it has a lot more space than needed for just the OS and Apps?
That depends on what sort of files you have in your home directory. If you have lots of music and videos or huge Adobe files your SSD could fill up quickly. If you just have office files like word, excel and powerpoint it usually isn't a problem. Of course you can always redirect the location of itunes, etc.
My home directory is 762GB so leaving it on the SSD is not an option.