I have a friend who makes quilted table cloths. She serges the seams on them, because unlike a bed quilt, they are washed much more frequently. She feels the serged seams will hold up better in the long run. I have not noticed bulk from the extra thread when sitting at her table.
If I was making a beach or play quilt, I would do the same. Serge the seams, so they can better handle the wear and tear.
mtpockets, god information about the industrial machines. The occasionally come up for sale around here. Do they need extra power to run?