Open top vs closed top action - how much difference?

[Caliper]

I've been pondering this recently and can't find much discussion on it.
A closed top action should obviously be stiffer, all else being equal, and it seems that this should benefit accuracy, but how much is this worth? I notice many, but not all custom actions are closed top, but is that driven by machine time, market expectations, or measurable benefits?

 

[Tokay444]

There will definitely be a measurable difference in resistance to bending force. As with all things, the market is predominantly what drives.
Ted at ARC has said a few times, “this is what people want.” One such instance is with integral recoil lugs. From an engineering standpoint, there’s little to no benefit, “but this is what you wanted.”

 

[b6graham]

Open top makes loading internal magazines much easier