I purchased and installed a Flytrex Core 2 in early October. Worked fine in my P2V+ for several flights. Soon after I started using it I noticed that Flytrex had a beta Version 4 of their firmware for the Core 2 which was to overcome one of the failings of the V3 firmware by time stamping the FPV file stored on the SD card. Great! So I installed the V4 firmware. The recording of flights turned into being very problematic. Some times data is recorded. Some times only the first minute or two is recorded. Some times nothing is recorded. Trying to download data from the "backups" stored on the Core 2 generates empty files. Additionally, one is supposed to be able to revert back to the V3 firmware. Well, that fails miserably. So I'm stuck with a non-functional (or hit or miss) flight recorder. At this point I have zero confidence in it. Several e-mails to customer service solicit a response "we'll get back to you..." but it hasn't happened for a couple weeks. Flytrex can't even take a couple minutes to acknowledge a problem and supply a response? Other Core 2 users out there: 1) Are you using the V3 firmware that came with the Core 2, and how is it working? 2) Have you upgraded to the V4 firmware, and how is it working? 3) Have you tried to revert to V3 firmware from V4? Did it work for you?