Running a 16GB Sandisk class 4 card, about 4GB free. Before the official AT&T nodo update, my phone was restarting a couple of times per day. Post update, my phone has been up 1 day 19 hours (so far) without a restart.
File this in the "for what it's worth" department: an acquaintance of mine works on the phone 7 application team at MSFT. He told me that the MSFT LG team had made a bunch of fixes to the SD driver, but the Samsung team was on a different release schedule and was not able to pick up the fixes for the original Focus release, but rather they were picked up in the nodo release. Given my results and the results I am reading about, this makes sense.