Only taken DXM 3 times, never going above 2nd plat. Yesterday I took 200 mg codeine orally, waited 25 minutes then took 50 mg DXM orally, waited 10 minutes and smoked a blunt. Wow, far, far stronger than I expected! My body felt fantastic, in a way it has never done before. My vision was completely fucked and I could barely read the text on my screen - my first ever DXM visuals were had.
Really nice combo, though I can't really recommend opiates for obvious reasons. Worth noting that 200 mg is, for me, a relatively low dose - i.e. no where near nodding just mild mood lift and pleasant numbness. I seem to by hyper sensitive to DXM though, as all three of my experiences have been below 100 mg and all three have yielded notable effects.
I'm only just starting to appreciate DXM. Having done a fair amount of classic psychs and a very fair amount of ketamine I can definitely say DXM offers something neither of these do...