For the speed of the phone not sure yet, will check that out once I receive the Note 3. I am thinking it will be pretty quick if it is able to shoot (4K) 3840x2160 video.
I just received the Samsung Electronics 64GB Pro microSDXC (UHS-1) Class 10 from Amazon and look foward to using it. Packaging/and reviewers list (Depending on the capabilities of the device) that it runs 70MBPS read and 20MBPS write.
Amazon.com: Samsung Electronics 64GB Pro microSDXC Extreme Speed (UHS-1) Class 10 Memory Card (MB-MGCGB/AM): Computers & Accessories
I originally ordered the SanDisk Ultra 64 GB microSDXC Class 10 UHS-1 Memory Card 30MB/s with Adapter (SDSDQUA-064G-U46A) It lists on the packaging 30MBPS read/10MBPS write.
http://www.amazon.com/SanDisk-microSDXC-Memory-Adapter-SDSDQUA-064G-U46A/dp/B007WTAJTO/ref=sr_1_2?ie=UTF8&qid=1380556502&sr=8-2&keywords=64gb+micro+sd
I picked Sandisk originally because that is the manufacturer that I usually had gone with in the past. After noticing the speed difference listed I decided to go with Samsung (The phone is also Samsung). There are not as many reviews for the Samsung memory, but if you look at the ratio Sandisk/Samsung.. Samsung is higher, and only ~10$ difference. Seemed better to me. I ordered both this past week and decided to return the Sandisk (Not used/opened either yet so can't fully review both other than what the reviews note on Amazon.)