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Yes , I agree that there are more than one way to skin a cat as they say.
We don't know how thick the mirror is , but for a passive triangle type flotation even 9 points are needed for a `full thickness' 12" mirror.
Single ring supports are a unique situation in that the bending of the mirror just causes a distortion that is part of a conic sesction and can be focussed out by a slight change of focus. Technically a 20" X 2" thick mirror will still work admirably on a single ring support ( with essentially infinite points in the ring).
A more complex variant of the single ring support used that is used professionally , is the multiple ring air bag support . The 2.3 metre Zerodur equivelent mirror of the ATT at Siding Spring, is only 6" thick ( 1: 16 ratio) and supported by two ring linked air bag supports whose relative pressures are controlled by gravity controlled pistons/valves to alter the ring pressure according to the pointing altitude of the telescope.
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