Only other type of fluid I have used in an X-310 is American DJ Fog Fluid, and the stuff is pretty much the same as X-Fog (Same family of companies). X-Fog Pro will hang in the air longer then regular X-Fog will, and X-Fog Ice evaporates even faster then X-Fog.
Other then that, I always try to use the fluid from the manufacture just to be on the safe side. Don't feel like replacing heaters and pumps on fog machines costing as much as these machines do. A little extra cost is worth it in my opinion, and Elation already has great performance per dollar on all their other products.