I'd take both out and see if either is really going to make you that much happier for spending the extra on a different model.
Personally I'd love a 370z but not sure that spending 15-17k would actually make me much happier.
Avon zz3 on mine are a really good improvement over the RE50s, noise wise quiter and grip both wet and dry much better. I got a full set for circa £550.
Would definitely recommend.