I also think OPS double counts, since OBP and SLG both include the same hits. I've seen an argument somewhere, though, maybe by Mike Elias, as to how the measure can be valued.
A few years back, I tried to come up with my own metric - productive plate appearances - that would account for hits, XBH, walks, sacrifices, steals, etc., but it just came across as too complicated. I also wasn't sure whether/how to account for especially unproductive PAs like a GIDP.