tedster - 9:02 pm on May 29, 2013 (gmt 0)
I think the key is not to allow the text in your comment area overwhelm the actual content your wrote. Depending on how big that content area usually is, you may find that 10 is best, or 30. It's a judgment call.
I don't think a canonical link for extra pages would do you much good, unless you don't want those pages in the index. That might be a good choice, however, depending on how useful the comments actually are. Again, it's a judgment call for your specific site with no absolute rules.