I have a Sandisk in mine. If you read the reviews on Amazon, there isn't any such mention of the UHC-1/Class 10 cards unmounting. Not sure, where you heard/read that.
If its this forum, after the phones and time I've spent on here, these forums, are primarily complaints. Rarely do people speak up/out to rave about something, but they'll certainly stand up on a soapbox to tear it down. So, every issue with the phone, seems blown up to grand proportions here, when in reality... its not widespread.
The SanDisk also smokes most everything in speed tests... consistently.
However, there IS a problem with counterfeit cards and some refurbs that were illegally relabled.
Again though... the SanDisk are great cards, with a great history of being stable/reliable memory storage options. You can get the 32GB for about $28 and the 64GB for $50 - $53.