Well, as per usual, I went overboard. Bought both the Lock and Lube and the DeWalt Battery gun. The Lock and Lube is stand out better quality than any of my other manual guns. It was $80 compared to the $20-$30 I paid for the others, but well worth it I think. I only did some ATV greasing with it yesterday, but it works well and loads easy.
I did the tractor with the DeWalt this morning. First the kinda negatives: This was a pain to load with a cartridge. I wonder if most people use bulk grease with these? Maybe there is a trick to it that I haven't figured out yet, though I followed the directions exactly. We'll see what happens with the next cartridge. Once the cartridge was in, it was super easy to purge and get going. The second negative, totally on me, is that I can't gauge how much grease is coming out. I generally have a good feel with a manual pistol gun, but just had no idea here. I was just doing very short hits of the trigger for fear of shooting too much grease in a fitting, which might be my problem.
Otherwise, man, a battery gun is a pleasure to use, especially on something like a tractor with a bajillion zerks, and the DeWalt is built like a tank. Once I get accustomed to it, I think I will be using it a lot.