All

I have an Instinct and a Fenix and I'm really happy with the wrist heart rate readings. Not much deviation from what I get from the strap and I absolutely hate wearing straps. You're right about the Instinct, I have beat mine to hell for years on the road, dirt and water and it hasn't lost any performance. Hard to beat for the money.

Yeah my wrist stuff is accurate during normal activity but its all over the place on the MTB and dirtbike I guess the way your wrists get bent, I wouldnt care to wear a chest strap if I didnt have to get surgery for SVT a couple years ago so I like to keep an accurate eye on things.

Been wearing a Forerunner 255 for over a year now and it's great. Create a new activity type for Motocross and in that activity settings max out the GPS sensitivity. Makes for very accurate MX track readings and lap times. Buy some of the cheap tempered glass screen protectors. I had my last screen shatter from roost and my new one the protector did it's job and got cracked. I have good luck with the wrist HRM on the 255 doing MX. Much better than older previous Garmins. Mine tracks pretty well compared to my chest strap.

The Garmin Instinct is really hard to beat, its the cheapest of the rugged Garmins and has its own GPS and the battery lasts for over a week with quite a few activities using GPS. Wrist heart rate on any watch is useless while riding so if you care about heartrate get a chest strap and hook it to your watch

Litpro did a great comparison for us. I ended up going with a Garmin 255 based on their reviews and data. Search Litpro GPS device shootout in your browser.

My polar pacer pro, has a choice to select motocross for training/riding, which is cool. Personally, i stopped wearing any fitness watch. Triggers my anxiety watching heartrate and all the other metrics.

PLEASE make a 350 Triumph... An alloy "wishbone" style frame/KYB sprung/non-reversed intake engine mx bike is going to be great package imo.