tactix Charlie

If you want to accurately track HR, get a watch that can sync with a chest strap HR monitor. I have the Garmin Tactics Charlie and the chest strapnHR Pro which is waterproof so you can swim with it. It's probably too bulky for you, but check battery life. I charge my watch once every 3-3 weeks.

I wear a tactix Charlie, about 2019 vintage, daily. It gets loads of abuse, gets strapped on the outside of my drysuit and used in water rescue, it does about 1-2 hours of GPS activity a day and battery lasts about 4-5 days doing that. Without GPS use I get about 8 days battery life.

100% worth it. I've had my Tactix Charlie for 5 years now, and the display still looks brand new. The bezel is pretty beat up, but the sapphire looks flawless

Disable GSP, Bluetooth, HR, etc or buy a watch that is specific for ultra and adventure racing. You can find an older Garmin model with ultratrac for a reasonable amount if you’re not looking to break the bank.

I3 tactical for field work/deployment, Tactix for leave.

I spent good money on the tactix. It's great. I've beaten and abused it. It's a tank. Does all the smartphone nonsense and way way more. Lasts about 20~ days on a charge so I can actually get all the telemetry back when I sleep and it's useful.

Good lord, what are you planning on doing, ODA level stuff? An Instinct (Solar) tactical is probably all you really need, Tactix is has some serious features - like windage and range finder. Good luck!