I suppose it depends on how much you have to do but we have been there done that with homemade and this year with 17 geese 20 turkeys, umpteen cockerels and ducks we invested in a proper one and we did them all in a day! Well worth the money ( and a sinew pull as well, so much easier).
We found the homemade too fast or uncrontolable with feathers everywhere and ended up with torn skin. The whizbang is the washing machine one I believe , that is one we did not do but have seen the videos.... would like to see a video of it doing a black plumed bird!