I've been using huds to give my avatar needs that must be fulfilled (i.e., hunger, thirst. rest, bathroom, hygiene, entertainment and fitness) for 4 years now, starting with the Little Minders hud. Because I participate in family roleplay, it definitely adds to the realism. I even add the huds to my smartbot pets so I have to take care of their needs also, just like in real life. I also prefer prim and smartbot babies that you have to feed/change/bathe, but I can't afford to buy items for my human characters as well as my pets and babies at present. I also really enjoy growing and cooking my own food. Using these systems is my favorite aspect of SL right now, and has been since I first discovered them.