Aren't all rubbers produced by ESN very similar? Why should i buy a Rasanter R47 for 50€ when i can buy a DHS Gold Arc 8 for 25€? Where are the differences?
1. There are conceptional differences. The Rasanter series for example have a thinner topsheet, which allows for a thicker sponge.
2. There are generational differences. Early ESN rubbers used to have lots of catapult but not as much spin. Over the years, the emphasis would be put on more spin, with some rubbers still retaining much catapult, others not.
3. Even within the same generation, differences apply in the individual recipes.
The newer the rubbers, the higher the price is a pretty common relation.
But maybe, while being relatively new to the market, you still might be buying an older rubber - it is not guaranteed any new ESN customer opts for the newest formulas.
So much for the theory.
Practically, if you find the Gold Arc does the same for you than the Rasanter, save the money.