I seal the edges with invisible tape. So the joints are, in fact, sturdy.

Photo paper smearing -- printing in photo paper mode, no they don't smear. (of course, I haven't gotten them wet or anything yet to really test the smearability and don't plan on testing that.) I did print a few in regular paper mode by accident and they did smear - quickly and often! Even after letting them appear to dry. The ink was coming off on my fingers as I was putting the pieces together. I found the key was using printing using the photo paper setting -- no issues with the final print job afterwards.

I might look into the laminate if I can find a thin enough style, just in case I have a water accident around my dust jackets.