You need much higher doses of dxm to get the psychedelic effects compared to ketamine. Ketamine is a pretty safe drug when used responsibly and occasionally, especially because you can slowly dose to the required intensity and it wears off quickly. Like any drug there are risks involved. Most notably psychosis and addiction. Apart from the immediate toxicity, of course. And that is very much higher for dxm in my experience. It's also a very weird trip and it took me a while (2 weeks) for my brain to fully settle again, whereas with ketamine I would bounce right back feeling better than ever, which of course increases its addiction potential. What we didn't know back then is that ketamine is actual toxic to the kidneys in prolonged high doses, so yes, be careful.