I just looked up Lotus birth and read a number of articles about it, from the pro-lotus birth perspective. I have to say that I find their arguments less than compelling... there seems to be no actual evidence available that supports it, and many of the claims made seem really dubious to me.
Like look at this: "These intact Lotus babies lose no energy just trying to stabilize their systems in the early postpartum hours and this shows on all levels (relaxation, bountiful healthy weight gain, core muscle strength, fine & gross motor skills, and alert observation of the world around them). This could be called 'accelerated development' but that would be a misnomer: Lotus babies are simply undiminished by stress in a very stressful culture.
Their greater capacity for relaxation, compared to nurslings who had early cord severance and placenta loss, is apparently a metabolic foundation for life, and makes teething and other developmental stages much less distressful. It could be concluded that Lotus birth gives babies lifelong coping skills."
Sounds way too good to be true, if you ask me. A lot of them are unprovable altogether, which kind of sets off alarm bells for me.
That's not to say that there aren't real benefits associated with leaving the cord and placenta attached, I simply can't determine if there are based on the practice's proponents, who sound kind of like snake-oil salesmen to me. Basically, I'm skeptical.
My one problem with the practice itself (as opposed to the arguments in favor of it), is the part about rubbing the placenta with oils and herbs and salts to keep it from decaying... It seems to me that once it gets to the point where it needs such things, it probably shouldn't be attached to your baby! I wouldn't want a rotting piece of meat (which it is, at this point) attached to my kid. And while they cite the practices of chimpanzees as the big reason lotus births should be done (this argument has its own problems which I think are kind of self evident), I don't think you will be finding chimps rubbing salt on the decaying placenta after a few days.
Anyway, from what I read I can't see any reason to think this is a dangerous practice, and if it sounds right to you, then go for it. But I definitely think any claims about its supposed benefits need to be taken with several grains of salt.