Nice lookin ladies! To answer your question, yes, dimming your light will have the same effect as raising it, less photons hitting the cannopy will stretch the plant. As far as your questions about turning down the lights without effecting growth, everything you do to your plants will effect their growth. 
Raising or dimming the lights, in general, will cause stretching between internodes and also slow overall growth and reduce the harvest size. Again, in general, more light equals more compact and faster growth and overall bigger harvest. You may want to watch this video. It has excelent info on marijuana lighting and effect on growth. https://forum.spider-farmer.com/forums/topic/latest-dr-bugbee-interview-from-shane-migro-a-must-watch/
Hope that helps.
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