While waiting for my Mini 9 to arrive, I'm looking at SSD expansion. It comes with an 8MB SSD, which is fine for Linux, but a stretch for Mac OS X. There are basically 2 brands of SSD expansion : Runcore and Super Talent (STEC).
The Runcore is slightly more expensive : 16GB $78, 32 GB $127
than the Super Talent : 16GB $63, 32GB $109
There is a slower (2X slower writes, almost 3X on reads)
Super Talent : 16GB $49, 32GB $89
The big advantage of the Runcore is that the module has an integrated USB port. This allows Mac OSX to be installed on a Mac while the Runcore is attached as an external drive. This makes the install go much faster, and is simpler.
If you look at the high end Runcore vs. the Super Talent, the ease of installation on the Runcore is a slam dunk. For the 16 GB, the Runcore is only $15 more, with the 32GB, it is $19 more.
Comparing to the slower Super Talent is a different story. For the 16 GB, the Runcore is $29 more, the 32GB is $38 more.
Still, if this is something that you will use extensively, it's worth paying the extra $40 one time cost.
I'll probably upgrade the RAM to 2GB right away, install Linux and do the 32 GB upgrade down the road. It's somewhat hard to justify an immediate $130 expense to upgrade a $250 computer. Perhaps I can pick up a used 16GB from an upgrader.
This posthas a good rundown of Runcore vs. STEC