I like the EPS. I have 3, and they have all been trouble free. I think they're the best general purpose carry optic available currently. For a hard use gun, I prefer the 509t because it's a bit more rugged, and the mount is bombproof.
For a gamer gun like a Shadow2, the EPS and 509 have too small a window. I have SROs on my S2s. One is direct milled and the other is on a CZ Custom plate. There hasn't been any issue with mounting a wider optic. If I had to replace one, I'd probably go with the Holosun 507 comp.