That's a very informative post, and the dump is a very nice showcase of his skills.
A couple of point from a fabricators point of view;
1; Stretching and forming Stainless is possible without cracking and stressing, but it needs to be annealed as it is worked; to remove the resulting "work hardening". This however increases the cost of the finished product often for no great benefit.
2; With regard to the thermal expansion issue; This can be countered by using a thicker flange. Also, using a material of a different expansion rate for the flange will actually increase the incidence of cracking due to the differing expansion rates of the two materials. Joining the disimilar materials isn't really an issue (using the correct filler), but long term, corrosion of the mild steel flange can compromise the welded joint.
3; Another critical dimension is the weld bead; if the bead of a butt weld (joining two flat plates) or fillet weld (joining flange to pipe) exceeds the thickness of the material by too much; this will promote cracking due to the difference in thermal expansion of the weld and parent metal.
4; Regarding surface finish; I agree wholeheartedly! The appearance of a weld is testament to the craftsman who created it. It is his signature. A beautiful weld is almost always a functional weld. Good engineering always looks good!
Note; None of my comments are in any way meant as a criticism of this product, merely posted for clarity; it's very neat, well made and keenly priced
Cheers, Dale.