It pretty much is exactly the same thing but SbuilderX doesn't need an airport nearby and you can do some advanced stuff with your polys like:
fill to QMID 11
slice to QMID 11 (or whichever QMID level you're working with at the time)
make line (where a line is made from the perimeter of a polygon - this becomes your perfectly matched shoreline effortlessly).
set as hole (you make a hydro poly that encompases a QMID 11, make another poly that represents the island and set it as a hole in the larger poly)
convert to poly (a line 100m wide and 500m long can become a
poly 100m wide and 500m long)
I would personally use AB_Flatten for sloped polys rather that Legacy_LWM_Land _Flatten. I once needed a road grade reconstructed that was built after the mesh data was sourced. I made a line 75m wide with a vertex every 100m or so. I subtracted the lowest elevation from the highest and divided by the number of vertices, then I adjusted each vertex to the height of the previous one plus the calculated value so the line made a perfectly gradual slope as it wound it's way up through the canyon. I converted the line to a polygon and set it as AB_Flatten, the elevations from the points in the line remained intact. I spent a lot of time making other sloped polys to blend it in with the surrounding mesh but the result came out quite nice I thought: