I went with the astronomically priced 768 SSD no-nonsense approach as opposed to the experimental Fusion Drive solution since failure of SSD or HDD means total failure.
http://macperformanceguide.com/macmini2012-dual-drives-vs-fusion.html
They are showing the Fusion option of the Mac Mini and not of the new iMac. The new Mac Mini used two standard 2,5" drives. You can add two 2.5" HDD (like with the server version), two SSD or you can put in both one SSD and one HDD and combine them (or not) for a fusion drive.
The new iMac uses one 2.5" HDD drive on the 21,5" version or one 3.5" HDD drive on the 27" version and if you go for the Fusion drive you will get a Retina MacBook Pro styled SSD stick with it. You are right about the failure, but that is inherent to the working principle of the Fusion drive, because it combines two physical drives into one logical one while intelligently shuffling much/less used date between both drives.
But you can always just turn Fusion off (see the ArsTechnica article on that). So if you really want to save money, just get the base version and the graphic card you want to get and purchase an aftermarket SSD stick from OWC for the Fusion drive or in your case both the SSD stick and a 2.5" SSD drive, for even higher all SSD storage space at a cheaper price. Of course you need to take the iMac apart, but since the screen is laminated this should be easier then before...The 786 GB all SSD option is just waaaayyyy overpriced...