I have a 72G Bowfront approx same dimensions and find the 6 bulb more than adequate for softies/LPS. Infact too high in the tank is too bright for some like you were saying. For just softies 8 bulb may be overkill HOWEVER........ if you may change to SPS, clams, etc you will probably want the extra 2 bulbs!
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45 Gallon Cube with 10 Gallon Sump, Lighting 8 bulb T5, Vertex IN 80 Skimmer
-2 Occelaris Clowns, Engineer Goby, RBTA, Peppermint Shrimp