I have a 2012 iMac with the 768GB SSD option. There is not enough capacity to hold 100% of my data (~ 1.4 TB). My configuration is as follows:
- 768 GB SSD: OSX, Applications, User Directories, iTunes database (sans media), full Aperture library
- Pegasus R4 (8TB): iTunes Media (music & video files) plus a Aperture library clone (updated nightly)
The reality is that streaming media does not need SSD speeds. However, OSX, Applications, and Aperture libraries benefit quite a bit with SSDs.
In my case, my A3 library is just under 400GB and growing at least 100GB/year (ever since I switched to RAW photos). I currently have 323GB free on my 768GB SSD... so I am probably good for 2-3 years of Aperture library growth unless I slow down on my photography (not likely). At that time, I'll have to choose (in decreasing probability):
1) Buy a new iMac, and give this one to my wife
2) Move my Aperture library to a new larger Thunderbolt SSD
3) Move my Aperture library to my Pegasus.
All 3 are viable... but I am already so spoiled by exclusively using SSDs (since 2008)... that I do not think I could stand moving anything (other than music & videos) to a HDD.
BTW: An external array (like my Pegasus R4) is significantly higher performance than an internal single spindle drive.
/Jim