Yes, if it's 300:100 or 150:50 so4/cl IIRC produce indistinguishable beers.
That has not been my experience. I fond that the absolute values are more important than the ratio.
100% agree with Denny. Forget ratios, focus on concentrations. A ratio is just a byproduct of the concentration anyway. While the example in quotes above actually uses the concentration values, they are technically both 3:1 ratios but will produce significant differences in the final beer.
As for how chloride and sulfate will affect your perception of the beer, it's not about sweetness vs bitterness. It's more along the lines of fullness vs dryness. Chloride does not make a beer sweeter, however it does increase a perception of a fuller (bodied) beer, and since it doesn't enhance the dryness then it may be perceived as "less dry" which folks might construe as "more sweet". A similar but opposite thing happens with sulfate where it enhances a dry finish which has the potential to increase perceived bitterness, and in turn reduce perceived sweetness (but that takes decently elevated levels in my experience). Some similar but different explanations can be said of sodium and magnesium as well in regards to perception of enhancing flavors and increasing minerality and/or bitterness. And, no, reduction of sulfate/chloride to low (but reasonable) levels does not make a bland beer or increase blandness.