Trazadone is an anti-depressant with sedating effects, not an anti-psychotic (and it's not a typical SSRI either). It might knock you out, depending on your tolerance to it, but I agree it's probably more likely to make things more confusing. The anti-depressant effects may dull a trip, but you need to take a fairly high dose for awhile to get those effects, I don't think it would act as an immediate "abort", unless of course you did end up falling asleep (not likely while tripping).
It gives me the worse hangover, worse than anything I've ever taken (or drank for that matter). I get that burnt-out feeling, like I just smoked an ounce of pot, for at least the entire next day. An awful pressure in my head, irritability, and the "cotton candy brain" feeling as I like to call it. Nasty stuff imo.