I use a LEM big bite 8. I've only ground elk and I don't add any beef or pork fat or meat. Elk only. I only grind once.
Last year was the first time I ground my own. I went overboard on trimming fat, sinew, silver skin, etc. All of it tasted amazing. But, it was very time consuming trimming and I'm sure there's tons of nutrients lost by trimming out all the day an connective tissue.
This year, since it's elk, I decided to test my grinder and see how good the elk tallow tastes mixed in. I want all the good stuff the elk has to give. So I trimmed the largest chunks of tallow and tendon off so that I didn't get a frozen pound of 50/50. All of this has tasted amazing too!! No gamey flavors at all. You do get the slick mouthfeel from the tallow, but it still tastes good.
Everything that wasn't big enough to use as a roast or cut into steaks went to grind.
I saved all the tallow I cut off so that I can use it for something... Not sure what yet.
And my grinder handled everything I threw in very well. It never bound up even though I got a couple of large tendon pieces in there.