i agree with all of the above, juicers never get to the efficiency of a good press, but some of them do ok, and it does depend on the apple as well. i usually don't have access to a reasonable press and make a good few 5-10L batches with a juicer or hand pressing each year, with these small batches and cheap local apples or freebies from friends it's not a problem. punky soft varieties don't juice well at all in my juicer and just turn into applesauce, firm apples do really well. hard crabapples are amazing, the waste is totally dry.
as stated above, it's a good idea to try a small batch first; if you have to clean the thing out every 5 apples and it takes you hours to get a few liters, then it's probably not worth the effort. however some people say that lots of pectic enzyme will help with mushy solids. i don't have experience in those matters... but- mushy waste from the juicer can be cooked and sieved into applesauce, or the hot juices from it strained off, polluted with rum and spices, mulled, and used as medicine, i have extensive experience here