If you are happy with what you have keep it. You know that car especially IF you had it since brand new. Versus a Sky redline that you have absolutely NO history on AND have no idea if it was abused.. I would keep what I know.. However, IF the offer is good, and you want to gamble on the Sky, have it, but be prepared for issues..
If you don't love what you have, sell it..
If you don't love what you have, sell it..