How important are ingredient ratios in pasta-making (as compared to baking)?
Proper hydration of flours is important in pasta making, so ingredient ratios are critical.  How critical depends on the type of pasta (egg based fresh pasta is probably more forgiving than water based pasta that is intended to be extruded and dried).  So, it sort of depends on why you are asking the question.  For a restaurant or pasta company looking for the best quality and consistency, it is essential to have the proper ratio.