[Focus General] jsgiv:
So - to add to the list:

I've had the Patriot 16GB Class 4 card in my phone (Samsung Focus) for about a week now - though not without it's problems:

Initially the phone, without a card, was fast and fluid/smooth.

When I ordered the card - I searched around and noted the issues related to SD cards popping up. I came across Paul Thurrott's writeup here: (windows phone secrets.com/2010/11/06/samsung-focus-microsd/) and, not wanting to pay $65 for a card that you can typically get around $30 - did some research and determined that Patriot ONLY made one Class 4 16GB card: (patriot memory .com/products/detailp.jsp?prodline=4&catid=16&prodgroupid=78&id=986&type=15).

I ordered this specific card (PSF16GMCSDHC43P) from Newegg (didn't want to order via Amazon 3rd party retail store) (newegg .com/Product/Product.aspx?Item=N82E16820220524&Tpk=PSF16GMCSDHC43P) and received it about 8-10 days ago prior to going on a business trip, etc.

I installed the card - uploaded about 10-12 GB of music and apps - and noticed hitting the "wall" with regards to syncing data to the device around the 9-10 GB limit. The music did continue copying - just at a slower pace.

I then went on my business trip and using the device was "ok" - but not great. There was *some* notable overall performance degradation. Overall - I kept using the device and, at times, it seemed to be getting better - but then times were worse - especially with regards to accessing the marketplace, etc. (which I'm convinced is a totally separate issue from these cards working).

While browsing around on my most recent trip - (2 in 2 weeks) - I started running into some issues with the device where it'd start hanging pretty badly. It was to the point where I was considering removing the card, resetting it, and waiting for a "fix" like everyone else.

However, I came upon a post on another forum that a user indicated that he/she shutdown the phone, removed the card, removed the battery, waited about a minute, placed the battery back in, re-seated the card, and rebooted the device. Once those steps were completed, the user indicated that the device was back to "normal" with regards to overall usability of the device (no lagging, etc.). The issue (according the user) is related to a known "tethering" bug when you sync the phone to your PC.

So, I followed those same steps and voila, I'm honestly, really amazed at the overall difference. It's as though the phone was reset to factory settings (with my card still in the device and usable). I did notice on the first re-boot after re-seating the battery, that the phone took a bit longer to start up. I'm not sure if the phone was performing an additional check on the card, or what during that time.

I've since sync'd even more music and apps to the device without issue (no resetting of the battery this time). One thing to note is that the marketplace is still noticeably slower during it's searches, etc. However, this is both on 3g AND via private/home network. While I believe there are obvious issues with some of these SD cards - I believe there's also some issues with the Marketplace/XBox Live apps too that need to be addressed. Prime example is initially, the apps are fairly quick, however, eventually, these apps will "hang" - to the point where they won't launch at all. Once I reboot the phone - they're back to being quick/usable again.