I use both heavy and light portable shooting benches to make longrange groundhog kills in PA. Without a doubt, the heavy bench is MUCH better for shooting.
No need to buy a bench because they are very easy to build. My heavy bench has a double 3/4" plywood top, 3 cast iron plumbing flanges on the bottom to accept legs and threaded pipe legs of appropiate length.
You can get fancy and angle the flanges out a bit for additional stability and design a bracket for the bottom which holds the legs when the table is taken down. You can also fashion adjustable length legs by using a smaller diameter pipe inside a larger diameter pipe and use a set bolt to lock them at any length. This really helps when the table is on uneven ground.
I painted the whole set green so that it is not obvious when I leave it afield when taking a break.