It's difficult to quantify the intensity of things like DMT, 5-MeO-DMT, or salvinorin A. I guess maybe an argument could be made that vaporized DMT is more intense than vaporized 5-MeO-DMT simply because the DMT experience is more variable. The less variable effects of 5-MeO mean that, on subsequent attempts, you can prepare a little better for it. It's always a dissolve into egoless white light type experience whereas with DMT the mothership is uploading the knowledge of different interdimensional alien civilizations each time. For the person trying each for the first time though, I'd say they're about even in intensity. I've not IV'd DMT actually -- didn't mean to imply I had. I was just acknowledging that it's going to be the fastest route. I don't think there's a huge difference in the experience of IV vs. vaporized, it's just that some people IV to avoid the harsh smoke is all. Whether you tie off, IV, then let loose or take it all in in one or two vaporized lung fulls it's gonna blast you about the same.
Regarding the vaporized DMT/5-MeO-DMT combo: I think Erowid has a report on that. I think the combo could be good, but maybe not to everyone's tastes. 5-MeO is more of a straight to ego death vaporization experience whereas if DMT is gonna kill your ego it's gonna make you understand exactly how the murder is happening. I imagine the combo would be like DMT alone but with more warm white dissolution.
While I stand by my opinion that 5-MeO-DMT is more intense than DMT, you make some good points I just have to comment. Actually I'm going to play a little devil's advocate with myself and partially contradict some of the opinions I stated earlier in this thread.
One thing that can make DMT more "frightening" (in lack of a better word, I'm not really meaning intense either) is that you actually have some time to be present in the moment and witness your ego being dissolved. It happens fast, very fast, but not so fast that you aren't able to catch up. I gets intense, more intense, and even more intense until you (maybe) eventually experience a breakthrough. 5-MeO-DMT shreds you to pieces so fast you're pretty much gone before noticing it. Many people I've seen smoking 5-MeO-DMT (especially the first time) "freeze"; they forget to breath out. Some drop the pipe (I'd hold it for a first-timer). The come-up is so rapid there's not necessarily any time to think about or feel fear. With DMT you have this little space of time where you feel you're travelling into hyperspace.
Also, even on breakthroughs DMT always leaves some part of my ego intact. It may be such a tiny part I hardly notice it, and it's definitely an ego-death. 5-MeO-DMT is the only psychedelic that completely annihilates every single part of my ego; I cease to exist. This difference also means that I'm more aware with DMT, and awareness can induce fear. With 5-MeO-DMT, there is nothing to feel fear with, because "I", the experiencer, is gone. In this sense DMT is more explorative. And that is one reason I like DMT more. It's more like a journey, while 5-MeO-DMT is more like being frozen in time. Everything stops. Everything ceases to be. The only thing left is the white light, eminating from inside and outside, immersing you completely. I suspect seeing and experiencing this light (which is usual on 5-MeO-DMT) is why some are convinced they have met God; why some atheists become agnostics; why some feel they have reached Samadhi. This experience should not be underestimated. It is extremely powerful. While not much else necessarily happens, this white light, which I personally perceive as a life-eminating force, can be
everything. There's no colourful visuals, no landscapes or entities, no elves or dwarves like with DMT. But there need not be. It's not a characteristic of 5-MeO-DMT. It's definitely characteristic of DMT and without the otherwordly visuals the DMT experience would be derived a huge deal of its richness and beauty.
There's certainly no denying in that DMT is more variable. More unpredictive. But I would never, ever say that 5-MeO-DMT is generic because the experiences are less variable. You have a better understanding of what to expect. But although I've taken maybe 60-70 hits of 5-MeO-DMT, I still have butterflies in my stomach every time I lit the pipe. I don't think I'll ever be fully prepared for 5-MeO-DMT. And maybe that's because
I actually know what there is to expect. That's another way of looking at it. Both the uncertainty of what DMT will give you, or the stronger certainty of what 5-MeO-DMT will give you, can contribute to the intensity and fear. But we are talking about preparedness now. Not actually being immersed in the experience.
If intense would equal fear (which it partially does for me), sub-breakthrough doses of 5-MeO-DMT would be far more intense than DMT. That is why I always aim for a complete breakthrough with 5-MeO-DMT. DMT can be thoroughly enjoyable, yet mystic and profound without breaking through. IME, this does not apply as much to 5-MeO-DMT. Awareness of my ego and body can be horrifying on 5-MeO-DMT. Because I am there, present in the moment, to experience all emotions and actually understand and interpret them with my ego. And my ego can do nasty things on 5-MeO-DMT (the most usual one is convincing me I'm dying or have killed myself); much less so with DMT.
Edit: Lastly, 5-MeO-DMT lasts considerably longer. I actually mean considerably, even if it means 10-20 minutes versus 5-10 minutes on DMT. Time has no meaning on these compounds. However, on DMT I'm sometimes almost disappointed it's over so quickly. 5-MeO-DMT seems to last for an infinity, and I never hope it would have lasted longer.
Edit2: If it confuses you that I say 5-MeO-DMT doesn't induce fear because "I" doesn't exist and say it can induce intense fear, I'm talking about breakthroughs and sub-breakthroughs and the difference beween them.