Well, chemically, they're very similar. They are both N,N-dialkyl 5-MeO-tryptamines, as you say. In 5-MeO-DMT, both those aklyl groups are methyl groups. In -MiPT, one is a methyl, and one is an isopropyl, so, essentially, it is a methyl which itself has two methyl groups bonded to it. Yeah, they are not one and the same, I'm not claiming that, but they have relatively similar receptor affinities. It depends on the ROA; I imagine you didn't smoke moxy, and I think if you did, it would be a reasonably worthwhile experience in forming an idea of what 5-MeO-DMT is like. They don't have "completely different" effects, I mean, they're both non-visual psychedelics, it's not like we're talking about heroin and cocaine, feel me? I think having a sitter would be wise.
DMT and MXE is more than challenging. Again, have a sitter, or at least someone else present.
fg, so it sounds liek that first one you mention is a chlorinated methylphenidate analogue, like 3,4-CTMP but not quite. 4-methyl-pentedrone sounds horrible, but I'm not so much into derivative cathinones, so do what thou wilt.