I actually see huge drecreases in the uniques of every domain I have ever had in Godaddy Cashparking, as compared to the other services.
I have posted this before, but I will post it again. The only instance when I recommend using GD CashParking is if you buy a lot off of TDNam. If it is free if you get a Discount Domain Club membership, which is also worth it if you get a lot of stuff with them, otherwise it is not worth the money, and in fact does not offer as good a system as the other services. Make sure that if you use the Discount Domain Club and get CashParking with it, that you set your domains to automatically enter your parking account and start making money on them immediately. If you buy a lot of domains on TDNam, this is expecially important. Godaddy does not tell you a domain enters your account until almost a day later. If you don't have your domains set to automatically park with them, you have two options. One is to let them park your domain themselves until you find out it is in your account. You then move the domain somewhere else and Godaddy keeps the parking revenue generated thus far for themselves. Or two, you have to check your Godaddy account constantly (multple times each morning), to see when the domains you were expecting to enter your account do in fact enter your account, and then move them ASAP, so that you don't lose money. I think that the easiest option is to just have them automatically enter your CashParking account, then you can move them out as soon as they notify you that you own them at the end of the night and you make money (hopefully) in the meantime. As I mentioned earlier, this only really makes sense if you get a lot of domains with them.