That shade of Gray is certainly capable, but it must be matched with a PJ with sufficient lumens. What are you using?
btw, any of the Daler Rowney or Folk Art's acrylic paint can replace the Liquitex Basics?[/quote]
Not and be considered a SF 2.1 application, or any official SF compilation.
The components are carefully chosen and evaluated, so as to work effectively and in balance with each other. Substituting leads to a "crap shoot" degree of "I wonder if...?"
Not that it "might not work"...just that your results may vary wildly, and you alone must make the judgement call, and reap what you sow.
(...but, if I had listened to naysayers 10 years ago, I wouldn't be here today. Creativity can not flourish without some risk taking.)