I have posted on here many times on how I have a LEM #12 that I got about 6 years go, and I do 8-12 deer a year. I pulled it out last weekend to do a few deer with my brother, and I discovered it is a #8, .35 HP. And it has done more deer than most deer season warriors will ever do. It still looks and acts like a new grinder, and will grind an entire deer in just a few minutes. Clearly, it doesn't take much of a grinder to do a deer.
But get as big of one as what makes you feel good, kind of like buying a truck.
"Man is still a hunter, still a simple searcher after meat..." Robert C. Ruark