To my way of thinking bitterness is controlled by the amount, type and schedule of hopping. Sulfate has an influence on the perception of the bitterness tending to render it more assertive, dry and harsh to the point that where one has paid premium for noble hops he wants to avoid sulfate altogether. As I brew mostly beers that use noble hops my sulfate to chloride ratio is as close to 0 as I can get it. Nevertheless I can brew very bitter beers just by using more hops and beers in which the maltiness is louder than the bitterness by using fewer hops or later additions. But maltiness and hoppiness are different 'principal components' of taste. They don't offset one another though I suppose you could argue that one can tolerate more bitterness if the beer is very sweet and that a sweet beer would be mawkish if you didn't increase the hops.
Chloride and sulfate concentrations represent two degrees of freedom. Chloride concentration and a ratio or sulfate concentration and a ratio also represent those same two degrees of freedom. If it is more convenient for you to think in terms of a ratio then you should do so but I wouldn't take the 'this beer should have a chloride to sulfate ratio of x:y' admonitions too seriously.
You can get an idea as to what these two ions do to beer by adding gypsum and calcium chloride to finished beer. The tastes won't be exactly what you will get by adding these salts to brewing water but are close enough that you can use finished beer tasting results to guide you in your next brew.