Well, not that it’s worth much, but here’s my experience.
The first gas range I ever lived with was the cheapest builder’s grade unit that came with the repossessed mobile home I bought as my first house. Simply put, it sold me on the benefits of gas over any other cooking method.
After that, I had several electric coil ranges (the kind I grew up with) and an especially nice ceramic top electric range. Although I was most familiar with the coil style electric, the lack of control (compared to gas) continually frustrated me. And the ceramic was abysmally, maddeningly slow to either heat or cool. Ugh! I would never (willingly) choose one of those again!
Now, I’ve finally got a “nice” gas range; not the best, but miles beyond any builder’s grade unit. The flames on these burners seem to flare wider than I recall the cheaper range doing. Maybe burner design has advanced over the past 30 years to improve coverage & efficiency? I don’t know. But I can definitely say that I’ve learned to “undersize” the burner to the pan with this range.
Essentially, as I understand it, you like the concentrated “heat pad” characteristic of an electric coil, but you’re hoping to also gain the instant heat control of a gas flame. However, because the heat “projection” of a gas flame is wider than that of a comparable coil element, you have to both use a smaller flame diameter than you would coil diameter, and use a lower heat setting than you would with electric (because higher flame settings only send more heat around the outside of the pan). This small/low combination conspires to lower your heat input & slow your cooking!
Now, I will also state here that my new copper pans react much more favorably to the gas flame than my stainless (Copper Core) pans. But we both know that it’s not practical to change all of your cookware to take greater advantage of the control gas provides!
So, the goal seems to be:
Maintain the central heat focus of “heat pad” (coil electric/halogen/induction) ranges, while maintaining the instant temperature control of a gas flame. I think you’re on the right track with a flame “containment” device, but you just need something a bit more refined than your foil.
Maybe something like this?