Personally, I prefer grass-fed, free-range livestock products when I can get them. I'm okay with supplementing pasture with grains, as many farmers do. I just don't think feedlots and other mass-confinement practices are good for animals or humans eating them. I particularly like shopping at a nearby Amish meat market; we often buy a package or two of meat per year there. (It is MUCH cheaper in bundles.) Those animals have a fairly natural life, and I can see cows, horses, pigs, chickens, etc. outdoors on the way to the shop. Our food co-op is also a good source, as is the farmer's market in warm weather, and one of the international food stores carries farmed lamb. My preferences are based on a mix of philosophical, practical, and culinary points.
The article does raise a point that grass-fed beef is easier to wreck. If you're going to swap beef into venison recipes, buy grass-fed. If you're going to try grass-fed for the first time, read instructions on how to cook venison (also very lean) nicely. The grass diet makes for a leaner cow with less marbling, which is awesome if you want a low-fat diet, but you have to cook it gently or it will turn to leather. I recommend a crock pot for many cuts. Another good safety catch is to use a sauce with enzymes or acids, to help keep the meat moist and tender.