Changing lengths of ANY cord or wire will change its' impedance somewhat. If the cords are counting on a specific length to achieve a nominal impedance or are "fine tuned" at that specific length, shortening them might alter the results that you're currently achieving with them. The best thing to do would be to consult the manufacturer and find out from the horses' mouth.
I would suggest trying to keep each cord away from the other. This means power cords seperate from power cords, power cords away from interconnects, power cords away from speaker cables, etc... This may require some type of spacer or "tie" system if you've got a LOT of cords in one spot.
The reason for doing this is that it would minimize either magnetic or RF based interaction between the cables. In case your wondering, digital based products DO emit RF signals. As such, it is quite possible for the power cord to act as an antenna. Obviously, the more distance between cables reduces the coupling between them and should minimize any interaction between them. Once this is done, all you have to worry about is that most of the stuff is tied into the same electrical circuit. This is one of the reasons that using "floating" or "telescoping" grounds on some specific gear can make a noticeable difference. Sean