I've never tried the oxindole, but I've tried a number of different extracts: UEI, UEB, gold reserve, 15x, 50x. I've definitely gotten sick from them before, but never gotten sick off plain leaf. I find these extracts can have a crash or hangover effect a day or two after as well, which doesn't happen with plain leaf. It's hard to say how dangerous these products are because we don't know what's in them exactly. I don't think they're dangerous, given the lack of deaths associated with them (other than that brand that had a tramadol analog in it) but better safe than sorry. Start low and proceed slowly.