1) If the equipment manufacturer recommends an I2S cable, then you should probably follow their advice. PS Audio is another brand that recommends using an I2S cable for their DAC's. There is a lot of positive comments regarding this subject on the PS Audio forum.
2) Check with both the DAC and Cable manufacturer to be sure that the cable you are interested in has a compatible "pin configuration" before buying the cable in order to avoid buyer's remorse.
3) +1 on the DH Lab I2S able. I find them to be a company that usually offers a "good bang for the buck" product.
4) When in doubt, don't start with an "entry level" product; but, don't start with a "top of the line" product either. Find a middle ground product that suits your budget and then go from there.
Best of luck and happy hunting!