BK,
I used Code Blue last year and I would suggest saving your money on it, in fact I don't think I'll ever buy estrous taken from deer. I'm going to start using synthetics this year. I was talking to a moderator on another forum and he mentioned to me that the hormones in estrous actually turn bad in 24-48 hours in the bottle, wax sealed or not. The reason for this is because of bacteria, resulting in an unnatural product. I'm not saying that you won't ever attract a deer that is rutting hard enough using "natural estrous", anything is possible.
I started checking out synthetic estrous and IMO I think it is the way to go. Once the synthetics touch the ground, they will also break down in 48 hours, but so would fresh estrous from a deer. The difference is that the synthetics are fresh and as long as they don't touch dirt you can use them from year to year.
After chatting with some people on other forums I came to the conclussion that I am going to try the following products this year:
www.trophyadvantage.com crystalized product that when mixed with water yields a gallon. Retails for $18 plus s&h. I've not done so, but I guess you can call the owner and he will gladly talk to you about his product
and
http://www.appalachianwhitetails.com/