[theoj]

Does green convert better than red? Performable seems to like red over green. http://blog.performable.com/631526233/

[cabalamat]

I wonder whether orange would perform better than red. Orange is a striking color, and doesn't have the same connotation of "stop".

[count]

Orange has 'warning' and 'slow down' associated with it here in the US though (think of every traffic warning/construction sign and highway equipment you've seen).

It couldn't hurt to A/B test though!