My iMac is doing fine and I'm sticking with it for the foreseeable future. It may be possible to swap the fusion drive for an SSD, but the procedure is way beyond my abilities.
Having once trashed a Mac mini when upgrading the HD I did not want to take a chance on the one I had. So on a Monday, I overnighted my Mac mini to OWC in a box they provided and for a very nominal installation fee plus the cost of the hardware OWC upgraded the SSD portion of the Fusion Drive to 1TB and had the Mac mini back to me by Friday.
OWC restored the data on on the Fusion drive and configured it as a single Fusion drive. It took one cut and pasted terminal command to separate the two portions of the Fusion drive into separate drives. Although I had been satisfied with the speed of the Fusion Drive, going to an all SSD boot drive blew me away.
