Epic is available in lots of different fabrics. It is basically a normal fabric that has been treated with silicone in such a way that each thread is coated individually. The fabric will therefore shed water much more effectively than a similar fabric treated with a DWR on the outside only. According to the manufacturer, this water repellency is good for the life of the garment. I have obtained a bunch of samples because I am looking to try it out myself, to see if it delivers. Alpkit do some waterproof jeans in Epic denim, called Jeanius, for £55. Rohan also do a version of their trousers in it, and a matching jacket. Orvis do a wilderness jacket in it as well.
The claims for the fabric are that it breathes much better than a membrane-based performance fabric, but will eventually wet out, and will not withstand water under pressure, which will seep through the weave. However, I saw a sample at the Outdoor Show being squirted with a continuous stream of water all day on the Alpkit stand, and even in the afternoon it felt bone dry on the other side. Very impressive! But I really would like to see how it performs as a garment in prolonged wet weather, and how the proofing lasts over time. If anyone has any experience, please let us know! Otherwise, I'm hoping to make up a jacket and/or trousers to do a comparison with Ventile, which seems to be the obvious alternative (ie not waterproof but weatherproof and more breathable). Hope that helps!