This survey? A 48% response rate's still higher than most election polls. And yeah, 52% of the surveyed homeless in the CoV are from elsewhere in Canada; only 8% outright said they were locals. It's also fair to assume the proportion of DTES problem cases is the same.
They should be free to go wherever they want, and I'm sure there's more than a few homeless Vancouverites who moved to Burnaby - less so, due to lack of local services -
but the fact remains that freedom of movement is making Vancouver's problems worse than if everybody stayed in place.
Edit: 80% may have been in Vancouver for more than a year... but 44% say they've been homeless for
less than a year (i.e. sans a time machine, at least 24% aren't long-time CoV residents). Exempting a few edge cases who may have moved in and been kicked to the streets within the span of 11 months, I'm going to go ahead and presume "not local."