I've grown to like collagen casings vs. the real thing. For one, it's much faster loading the nozzle. Second, when you cook them, the sausage expands a little past each end. the collagen casing does not. So, once cooked, it's really simple to slice and pull the casings off - it comes off easily, leaving you a nice sausage with no casing at all.
Note this doesn't work with snack sticks. You still gotta deal with 19-21mm sheep casings, which is a real PIA, but damn they're good!