If you think this co-writer can take your song into the magic land of success........why not? If you don't think he can take it any further than you can yourself then don't. Its really about what they have on their resume unless you just want to share with a friend co-writer or take some gambles. I would think the best chance for significant success is having an notable artist that has heard your song and wants to record it rather than someone just modifying your song for their own desires. Having said that, request hearing their music and investigate their talents--then you can make a better decision...........

steady-eddie