In certain example embodiments, a multi-layer undercoat may include a layer of or including tin oxide on the glass surface and a layer of silicon nitride thereover. Tin oxide is advantageous in that it is relatively durable, and is a low stress material with excellent adhesion to glass. Moreover, the sputtering rate for tin oxide is several times higher than that of silicon nitride. Thus, problems of high cost (due to slow deposition rate) and durability (due to high compressive stress) can be overcome through the use of tin oxide as a bottom portion of the dual layer overcoat. The coated article may or may not be heat treated in different embodiments of the invention.