I raise 100% grass fed Ruby Red Devon beef. Just wanted to put in my two cents on how to NOT get a wonderful experience out of grass-fed.
1. cook it too hot or two fast - it's OK to sear it but then put it on a cooler burner - don't turn down the burner it's on - the heat stays too long - have another burner to put it on. Think venison.
2. get too young a beef - it takes just about 3 years to properly finish a beef on 100% grass. My meat is as well marbled as any feed-lot beef but it takes the extra year to get a beautiful marbeling on grass only. This adds to the expense of raising the beef, thus be prepared to pay for that.
3. make sure the beef was finished on GRASS - not hay (which qualifies as grass) - especially in the winter - have your beef finished while they are still on pasture. Hay tastes NASTY.
4. Make sure the animals are handled and killed humanely. If they are stressed, their adrenaline is in their system and the meat is dark, tough and doesn't taste good.
5. Sounds counter-intuitive, but be careful of organic beef. The USDA has approved incinerated bio-waste as Certified Organic fertilizer. It is CHEAP and certified - thus a LOT of farms use it. It's cheap as that's one of the only ways for the government to get rid of it. The farms I know that use it have to shut their windows when it rains - as it still smells like poop. If it smells like poop I am sure it effects the flavor. EEWWW is all I can say.
6. Make sure the beef has had access to the right minerals - if they don't get free choice minerals their muscles are deficient in anything their grass is deficient in and this effects the physical properties of the muscles - and thus the tenderness and flavor.
7. KNOW YOUR FARMER and don't be cheap. Same rule for any produce or meat you are buying - you don't know what you are getting if you don't know the farmer. It takes another year to raise a perfectly finished grass-fed beef and if you want that experience you should be willing to pay for that. You pay extra for hand made furniture and a good grass-fed beef is really crafted, not thrown out in a yard then killed.
I have beautifully marbled, melt in your mouth, great taste from first bite to last, beef. But it's a lot of hard work and requires daily pasture movement and care of the animals and lots of time and patience. You get what you invest in - in money and in time investigating what you are indeed buying. I'll place my beefs against any conventionally grown beef any day - and I'll win - but that's not what you get by just buying any old generic grass-fed beef for the most part. Investigate ALL your food - you would be amazed at the crap that's offered us.....