My 2 cents:
I've been doing an alt. version of Bulletproof Coffee for about 2 yrs and have had good results. For my version, I use freshly roasted beans from my local farmer's market (they roast on site), Coconut Oil, and Stevia as a sweetener. I also use a mini aerator from ikea ($2.49) to mix it. This is very important unless you like an oily film on top of your coffee.
I use organic Coconut Oil rather than Grass fed butter for two reasons:
1. Coconut Oil is much easier for me to find
2. IMO, it tastes better than the butter
I tried the grass fed butter, and it was pretty good, but like I said. The coconut oil is much easier to find in stores and it actually tastes better. The butter does give the coffee a creamy texture that's good though, so I'd try both just to see which one you like better. I tried the MCT oil for a while and noticed that it can be a tad harsh on my digestive system, so I cut it.
As for results, in addition to having a significant boost in energy in the AM, I also noticed health benefits. My good cholesterol (HDL) was through the roof at my last physical. While my LDL was really low. My Doc asked what I was eating, and I told him about my Bulletproof experiment and he said it appears to be working at least for my HDL.
As for added benefits for workouts, I don't really notice a huge difference with coffee alone. When I add a NO2 booster to the bulletproof coffee, I do feel a big difference, but that may not be for everyone.
So, I said all that to say, it does work...to an extent. But I'd definitely advocate a DIY version rather than buying a bunch of overpriced products with highly questionable added benefits.
I hope this helps. I'd be happy to answer any other questions.