I bought one for use in time attack but I put it in our Lemons cars as well during races. We're the other way around... I actually turn off the lap timer display during races because I don't want my drivers fixated on lap times. We'll communicate pace to the driver over comms from our pit, but I'm fairly confident having lap timer displayed w/ a delta is going to land us more black flags. It's great for looking back at footage and reviewing data, and it's way easier to find footage since you can look it up based off time, lap #, and turn #.
I think it's better suited for HDPE/time attack/practice days... every race we end up with corrupted footage and data (not a huge amount, maybe less than 10%), and that corrupted data/footage always seems to be when something cool happens. The catalyst seems like it can handle endurance racing, but it doesn't seem like it was designed with endurance racing in mind. One annoyance is it's one more thing to deal with during pit stops. When you hit the kill switch, it turns off the camera (which is powered off the catalyst dock), after driver change/fuel, you turn the car back on but there's a delay between the camera turning back on+catalyst seeing the camera, once that's on you can start the session. Long story short, someone in your crew needs to be playing with the catalyst and you need to start the car earlier rather than it being the last thing you do during a pit stop. Finally, we've found that we end up with less corrupted footage if we stop the session, let the garmin save it, and then start a new session every driver change (rather than leaving it running as Bricoop mentioned). The coaching system also wasn't designed for use in a crowded field and with multiple different drivers. It's designed to work on an open track with one driver and to improve that drivers consistency and performance within their specific limits using their data.
It's been worth every penny since we'll use it between all cars (especially worth it for TA cars), but I personally wouldn't have spent the money on it for use only in endurance racing. The driving coach is the biggest selling point, and it's hard to apply w/ multiple drivers in a crowded field, we personally leave the lap timer display off, so during Lemons races we basically use it as a fancy dashcam. Resolution on the Garmin is also pretty good, but grainy when compared to a Hero 5. (we currently use both a hero 5 and catalyst).
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