In any reactor, 2 adjacent dual rods have the same efficiency, heat, and power generation as a single quad rod : they just occupy more space: so your reactor is essentially a 4 - separate - quad design. I.e a base efficiency of 3 - with a x4 bonus for being at 80% Heat.
This reactor fits 5 quads in:
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So its still efficiency x3 (x4.2 @ 80%).
I found this design in my list of interesting designs. It has a base efficiency of 4 (so, x16.8 eff at 80%), and uses duals:
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It is really hard to produce better designs than this that can run safely with no downtime and can be automated (rods all the same type and no components that wear out) as without overclocked heat vents you are really constrained by the amount of heat you can remove, and heat goes up faster than efficiency as you stack rods next to each other: You can't really boost efficiency using neutron reflectors, as the increased heat is all being delivered to a smaller and smaller number of components. I trialed a couple of Eff 4 designs using this approach but the dual design above already does that without a reflector, and 2 reflectors plus a quad rod seems probably impossible to cool.