Phils post is here — Phil's New Waste Board - #194 by FrankVargas – Titled "phils new waste board.
Curtis’s is here — Finally looking like an X-Carve again... well kind of - #40 by CurtisCummings – Titled " Finally looks like an x-carve again"… Both are in the x-carve forum under "upgrades.
They possibly could be used but in my opinion without the strength that the 90 degree angles gives you it wouldnt be much benifit, not nearly as much as having the angle in there anyway.