I used this in my tv-headend box and can easily record from both tuners at the same time three recordings and playback at the same time. They are U3 not U1 as the link states. The smaller capacities tend to be U1 not U3.
I have used a dozen of the Kingston ones but the U3 Transends seem quicker. I have had a couple of the kingstons go corrupt but re-flashing fixed them, it may have been just a power spike.
I did some read test in another thread
I think the read bottleneck is the microSD interface. Without the risk of being stoned to death for recommending it, if that’s a S912 box the fastest speed you are going to get is flashing coreelec to the internal flash. BE WARNED YOU CAN EASILY BRICK YOUR DEVICE. I will not go through the methodology as it not officially supported. I use this method on my X92s and they seem snappier. also the X92 uses a SDCARD which sticks out a lot so its neater for me to flash to internal. I have an X92 image so I can reflash the Android back if I need it.