For the curious, the LD50 in humans is thought to be somewhere on the order of 200mg/kg. So for a 70kg individual, that would be 14,000 mg (14 grams). A very strong coffee is 100mg, with energy drinks being 200-300mg.
Ethics committees frown on poisoning people just to figure out how much is lethal.
LD10 is plenty for me never touch it outside of a life threatening emergency.
Which is to say, no, I would not feel comfortable consuming the equivalent LD49 of a substance. It is an order of magnitude estimate to give you a sense of toxicity. Which in the case of caffeine - is so high that it is nearly impossible for a healthy individual to consume that much accidentally.