If I can put in my 2 cents in this discussion I will say that if you look around, you can get good deals on a good used commercial grinder with a little research and patience. Myself, years ago, I bought a used Stimpson meat grinder from a used equipment dealer for around 1k if I remember correctly. It has a pan 20"X38" with a #32 head. I have put more than 50 pounds in that tub many times . I used to slaughter and cut beef for farmers back in the days when we could do that and I tell you, this Stimpson grinder can take a beating; I had a guy pushing meat through it all day from the beginning of October, through the hunting season and freezer orders season up until Christmas every year for many years. Still have and use it every day. 40 pounds of meat in this grinder would take just a few minutes I don't know exactly how long but I don't think it would take more than 5 minutes at the most.
This being said, I have three stuffers: 1 TreeSpade 5 pounder that I use to develop recipes, 1 TreeSpade 15 pounder for my main stuffer ( but I can put 16 lbs. in it easily )and a 30 pounder (no name) that I use for very big batches although I don't save a lot of time compared to my 15 pound TreeSpade. I try to make my batches around 15 lbs.: 12 lbs. of meat + three lbs. for spices and water. If I have more than one batch to do, I first start by doing all of the grinds and separate them in different meat lugs. While the meat re-cools itself, I mix my spices then I mix the spices with the different batches. If I am making sausage in hog casing, I let the mix soak in the meat while I clean my grinder. If I use sheep casing, I stuff it right away because if I let it sit for too long, it gets hard to push it through the spout; specially if I use the long spout for 20mm collagen casing (in this case, If I use collagen casing, I put more water in the batch to make easier to push)
At this point, I don't know if I make sense or if I'm just babbling so I'll just finish my comment right here.