DMT is physically impossible to overdose on since your body can only absorb the drug for 30 seconds after the first hit. This is why some people just can't seem to have a breakthrough nomatter how hard they try. It's also the most likely of the three to actually be what you think it is since a lot of what's being sold as LSD these days containes Nbomes and a lot of X pills contain RC's. When you buy (or especially synthesize for yourself, which is mystifyingly easy) DMT, it's almost guaranteed to be DMT. DMT has also accounted for exactly 0 deaths compared to the 1 for LSD and a lot (no idea how many) from Ecstasy.
However, DMT may be short but that doesn't mean it's not powerful. It can be EXTREMELLY overwhelming for some people and you really do want to be ready when you break through. You never know what can be encountered when you're thrown into hyperspace. You may come face to face with a 50 foot tall insect-like alien and you have to know how to react to it without having it spiral into a massive and fully-real bad trip. It really can mess you up if you aren't ready but it can also teach you a lot about yourself and change you for the better as well.
As one of my favorite websites (DMT-Nexus) says best;
"DMT is a bottomless well of never ending confoundment, an unsolvable riddle of epic proportions spoken in alien tongues. It will call into question all that you know, all you’ve learned to accept as reality, and introduce you to a state of being which defies all comprehension.
This experience is not for everyone, and not all who choose to open the door deal well with the questions it raises. It should never be undertaken lightly or treated in a casual manner. Those who approach it with little respect often pay a psychic price.
Should you choose to proceed, be aware that integration issues may follow. What you find inside may change your life. It will almost certainly alter your deepest, most fundamental assumptions."