I have used both the on-line archives and the archives themselves. Digital access is fantastic, but you are at the mercy of how good of a quality document you can obtain from the source. I have just gone to try to access the 1861 Census on-line (ancestry & LAC collaboration) & for a lot of the records the pages with the names are missing. At the archives themselves that would not be a problem - but it is difficult to get a good clear print out from their printers. So there are pluses and minuses with both. If they do not put the other pages on-line as well you can miss out on some information that you may find important.