Maybe I can help. I used a terrapin a few times on deer and such. On flatland where you can really tell if a LRF will work or not. I ranged some deer little past 600 the other day looking into the sun. Ranged a flying hawk around 500. Actually ranged steam smoke or whatever coming out of a plant at 500 a few days ago, just thought that was crazy. I have ranged and airplane hanger at 5300 yds with my terrapin but you want critters. I feel good on deer past 700 or so. I realize it ranges much farther than that but the other day we were looking at some deer I was spotting and my buddy was on the gun. He has a 5-25 S&B. He saw 2 deer and I couldn't find em due to the lighting for quite a while. After I found em I ranged at 869. They gave me a little trouble to hit them due to the distance and visibility. Anything vectronix is jam up. I love em over ANY other brand. Hands down. I feel that if I can hit it and stay steady, anything under a mile is ranged given brush or something doesn't interfere. BUt I would say that deer are 800 or so in ANY conditions. I've ranged em way past 1K but sometimes in flat lands that is tough. And not neccesarly the LRFs fauly. Just the nature of the beast.
Hope this helps.