3HR vs 945 ?

In terms of why the 2 watches are in different sections of the forums, it's because their in 2 different product lines. Fenix falls under Outdoors meaning hiking and orienteering therefore a more rugged case design. While the 945 falls under Sports meaning running biking swimming where it doesn't need to be as tough so it can be a lighter less rugged case.

I've had an F3 in the past and can't think of anything that it has that the 945 doesn't. There may be some obscure menu item that some people use and like that's not in the new watch but I can't think of anything that I would miss if that was the transition I was making. I know there's nothing in the F5+ that I'm going to miss.

I was never convinced "rugged" was anything more than looks and indeed heavier materials than the ability to say actually absorb bumps. In some ways the fact they are different products makes little sense because the code appears to be the same. I think it largely comes down to what you prefer to have on your wrist. I take the lighter Forerunners.

I know some people that refer to the 935 as "the plastic Fenix 5" as they are really the same watch. They prefer the 935 because of the weight, and some claim that GPS is better because of the plastic case vs metal.