I can honestly say I've never traveled most of the canal paths, but I have heard from some in my club that vagrants can be found in some of the tunnels. Most are sleeping, but I did hear of one that jumped in front of a lady once, knocking her off her bike. I don't think he did anything bad to her, the story I heard was that he was only half there and wanted attention. Again, these are stories and who knows how true they are.
Still, I'd suggest a good light for commuting home in the evening. The more lumens the better so you can see far out in front of you.
Also, Phoenix seems to be a great biking community. Lots of great places to ride here other than commuting. Don't be afraid to join a club and do some weekend rides. There are some idiot drivers, but for the most part, I've had really good luck riding in the North Valley.
Hey guys, lets go play bikes! Strava