Edit... a little more optimizing of edges on the version with SubD, and I got it down to 800 quads with 1 iteration of SubD, and 200 quads with simple vertex smoothing.  I think that is quite acceptable for a button with a raised edge.  If I didn't extrude the edge to make it thicker, and if I decided not to chamfer the edges I'd probably get it down to a minimal 100 quads, but it wouldn't look as good under scrutiny, in close-up renders using today's unbiased physical lighting engines.  My concern about any object I model is how it holds up under physically accurate lighting conditions, because most of today's engines are VERY picky about how the object is constructed, and objects without much detail really look like crap when Path Traced.  If there aren't sufficient amount of segments, then artifacts and faceting begin to become aparent. Also, if I were to take an object, not a button obviously, but other objects, to 3D print, then detail matters.  You can't 3D print or fabricate a bump map or normal map. ;)

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