Like gbopp said. There are other brands besides Henry's and I would just go with what ever brand is available at your local big box hardware store. Some are even labeled RV Roof Repair EPDM.
I used a different brand on my 5er roof that was 10 years ago and the only leaks were on places I did not use the EPDM paint. I can not remember the brand, but it was on sale at a Do It Center for 50% off so I bought it.
I have used Henry's since then on other projects to waterproof everything from fence gates to boat hatches and it is a good product.