I bought an Intel 520 series 180gb SSD to use with my 2012 Mini i7.
Instead of mounting it internally (didn't want to open the Mini and have problems, as a number of others have had, as reported in this forum), I bought a plugable.com "lay-flat" USB3/SATA docking station. (with ASMedia 1053 controller chip).
Using the BlackMagic speed test utility, I get read speeds of 410gbps and write speeds of 247gbps via USB3. The write speeds might not be quite as fast as you would obtain through an internal SATA connection, but they're very, very good. And read speeds are nearly identical to what you obtain via internal SATA.
Also, there are no "random disconnects" that others have experienced, and no "sleep problems", either.
Oyen Digital makes a very nice 2.5" enclosure with an ASMedia controller chip, if you would prefer a "full enclosure" to a "docking station" setup.
I don't understand why more folks haven't considered this option.