What's the overall opinion on using these? I've seen several threads in the past recommending to stay away from SanDisk, but I find that kinda strange since SanDisk is one of the leading manufacturers of solid state memory.
the main reason people said to avoid sandisk, particularly on novatek chipsets, was software incompatibility. something to do with the way the firmware of the camera mounts the "disk", and the way sandisk presents the low level format info to the device. the camera simply refused to use the card at all, or sometimes would use it, but it would be very flaky and unreliable.
that said, i used a 64gb sandisk ultra in my novatek-based a118c without any issues (granted, it was very short term use - filled the card about 5 times to record a road trip), so maybe the latest NT firmwares have fixed this issue.
then again, as i said, that card died after spending a couple of weeks in my wife's CF-100 (with parking mode). i can see that there are files on it, but can't open most of them, can't format it, can't run h2testw, or much anything else. even the files that i CAN watch, i CANNOT delete. it's really weird. even tried some low level format utils to try to revive the card, but it's toast. and sandisk's warranty clearly states that your warranty is void if the card is used in any sort of constant recording device like a car DVR, surveillance system or cable-tv dvr. many other companies say the same thing - warranty void or greatly shortened when used in a DVR-type situation. so to replace this card, i bought one of sandisk's "high endurance video monitoring" cards. $40 for a 64gb, so not too bad:
https://www.amazon.com/gp/B00V5Q1N1I - hopefully it'll last more than 2 weeks