Hi absolude,
It would be roughly the same yes but there would be some variance depending on the properties of the raw natural latex (which varies) and on the firmness level of the latex. They would vary the formula slightly to make the end result as consistent as possible between batches or seasons but they don’t provide the specific compounding formula they use (which is proprietary information).
Some of the links in post #2 here may be of interest to you especially the last one which shows how close natural and synthetic rubber prices are. Of course natural rubber involves shipping costs that are much higher because it is sourced from SE Asia mostly (regardless of where it’s manufactured) while SBR can be produced from the raw petrochemicals anywhere in the world.
Phoenix