I have a Z7 and love it. The only thing I've done on it is to replace the string with a Winner's Choice. I did keep the original, with a little wear on it, as a backup for when I travel.
Personally, I would get the bow, sell it and buy something you need. However, if you're going to keep it as a backup or for new shooters, you might consider the Z7 because it's extremely smooth, easy to pull and pretty forgiving. Also absolutely no handshock and very, very quiet. (My dad was shooting his about 10 yards from me on Saturday and I could hear his arrows fly - Quickspin fletching - but couldn't hear the bow go off.) Might be a good bow for someone not feeling real sure of themselves when they shoot for the first time.