Bike footage usually fails for four reasons: vibration, wind, mounting and light. You have the light and the wind ones. For most riders at your budget I would get the Insta360 Ace Pro 2. Prices are US list as of 28 Sept.
Ace Pro 2 is $369.99 (single battery kit, $389.99 with two). 1/1.3" sensor behind a Leica f/2.6 lens, and Insta360 quote 13.5 stops of dynamic range. DJI quote the same 13.5 for the Action 5 Pro and GoPro give no figure for the 13, so for your tunnel problem it's really Insta360 against DJI. What tips it is the rest. PureVideo low light mode for the evening rides. It's the only one of the three with a flip screen, so you can aim a chin mount before you pull away instead of finding out 20 minutes later that you filmed your own chin. 8K30 means one pass on a good road gives you the wide shot and a tight 4K crop in the edit. FlowState with 360 Horizon Lock keeps the horizon level through the lean, it charges to 80% in 18 minutes and it's rated -20 to 45°C. Downsides: heaviest of the three at 184g, 180 min battery against DJI's 240, and only waterproof to 12m.
DJI Osmo Action 5 Pro, $319 at B&H. Pick this one if price, battery or weather decides it. 240 min battery, 20m waterproof (60m in the case), 146g, and RockSteady 3.0+ deals with handlebar buzz well. SuperNight mode for low light, and 64GB built in (about 47GB usable) as a backup if a card dies. Downsides: tops out at 4K120 so no reframing room, and the rear screen is fixed, so framing on a helmet is trial and error.
GoPro HERO13 Black, $429.99 list, though it's often on sale. If 90% of your footage is chin POV, HyperSmooth 6.0 is still the benchmark for that and nobody has more mounts. But the 1/1.9" sensor is a class below the other two and you see it in tunnels and evening light. Only waterproof to 10m, and the most expensive of the three at list.
Your other two: Luna Ultra ($769.99), don't. It has no water, dust or splash rating at all, and rain is not optional on a motorcycle. 233g as well. MISSION 1 ($599.99 list) is a very impressive camera, 1-inch type 50MP sensor, 8K30, 20m, but it's 207g, $230 more than the Ace Pro 2, and the wrong shape for a helmet.
Mounting. Chin mount gives the best POV and the steadiest picture, your neck is a better gimbal than any algorithm. It's also where weight shows, the 38g between the DJI and the Ace Pro 2 is noticeable on a chin bar after four hours. Side or top of the helmet is easier to fit but catches more wind and puts the weight in the worst place, fine now and then, not for every ride. Handlebar shows the bike and your hands but feeds engine vibration straight into the sensor, so use a damped or RAM style isolating mount. Tail mount is great for group rides and commutes, steady and almost no wind in the mic. Whatever you choose, tether it, check it before every ride, and check your local rules on helmet cameras.
Wind noise. Don't trust anyone ranking the built in mics with numbers. The makers list how many mics and a wind reduction setting, but none of them publish a measured wind noise figure. What actually helps, roughly in order:
- Record audio away from the airflow. Wired lav inside the helmet, or your intercom audio recorded separately and synced in the edit.
- Foam wind muff over the mic port. Cheap and cuts the hiss a lot.
- The camera's wind reduction setting. Helps, but doesn't beat moving the mic.
- Move the camera out of the blast. Tail or tank mount hears far less than a chin bar.
Carry a spare battery. Cold and vibration drain cells faster than any rated figure, and with a spare in the jacket the 180 vs 240 minute difference stops mattering. If you would rather choose the angle after the ride, a 360 like the Insta360 X5 ($549.99, so over budget, 15m waterproof, replaceable lenses) on an invisible selfie stick gives you the floating third person shot. The catch is any single flat view you pull out of it holds much less detail than the 8K number suggests, so if you only want the forward view a flat camera does it better for less. And don't treat any of them as a dash cam. Most have loop recording and the Ace Pro 2 can start recording when it gets power, but if you want a dash cam, buy a dash cam.
Which mount are you leaning towards? Mostly forward POV points to the chin. If you want the bike in shot, bar or tail. Happy to answer questions.