I think I have watched every video and read everything I can find. All I have found is opinions and preference, but I'm looking for facts. My goal is to set up a couple of channels (this would be my first) sometime soon. The plan is to do something like this.
https://youtu.be/UgC20Wtx0Eo
if you look at the 11:10 mark
There seems to be more advantages to using pvc pipe vs the gutter downspouts or fence post cover.
pvc pipe advantages
cheaper
more common and readily available
variety of fittings
more durable
available in more sizes
downspout/fence post cover advantages
easier to cut holes in, and keep them straight
avoids pooling better than round pipe
lighter weight
doesn't roll around
feel free to add to the list, while it will be more difficult to install the pipe with the spray heads inside a round pipe, it can be done fairly easy, which is what I am leaning towards.