Juan,

I was reading on the other S2 thread.  https://bitcointalk.org/index.php?topic=515448.2700
The newer S2 units have extra capacitors on the blades to help stabilize voltage.  See Bitmain's instruction here. https://www.bitmaintech.com/files/download/Guideline%20of%20Soldering%20Capacitor%20to%20S2.pdf

So do the units in the group buy have the following:
1) Extra capacitors solder on the PCBs?
2) Improved retention clips for the blades so the blades stay secure within the case during shipping?
3) Fixed SD card corruption problems that leads down time?

Thanks.