Yes that does seem like the best possible scope design. They've been built by hobbyist astronomers (even with truss tubes holding the secondary/eyepiece section and a "tube" made out of cloth to block stray light).
I'm not sure if they did over 4 times the primary mirror grinding just to use an off-axis circle-ellipse that's less than a quarter the area of the mirror. That sounds like a lot of work and waste to get rid of diffraction spikes. Imagine grinding a mirror about a yard wide just to make a 12-16" telescope. Although you could cut and sell the rest of the mirror or use it to build an imaging scope for each CCD or something and still make a small regular scope from the middle. Maybe if you're really careful it'd be less work to grind the side of a parabola without grinding the rest of it. Especially if they sell off-axis mirror blanks now so you don't have to buy the costlier huge mirror blank, cut it and then be burdened with a mirror blank that has a circle cut out of it. I don't know, I know almost nothing about telescope making.
Other hobbyist telescope makers have built 1-vane secondary mirror supports cause they prefer fewer and worse spikes; and curved secondary mirror vanes, which have every possible angle somewhere along it in equal amounts instead of just orthogonal or triangular one so they spread out the spikes into a less bothersome halo.
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