I don't follow you. :/ Most of the multiplat are good enough on ps3, lately; could be 360 could lead with a slight advantage, but now all multiplat automatically become horrible on ps3 because 360 has some edges? It's not 2008 again.
That's the problem, most pS3 multi-plats are 'good enough'.
Its sad to say but its still favorable in 95% of cases to buy on the 360 if possible.
Just look at Black Ops 2 for a recent example.
Is that 'good enough'?