DH and I co-sleep with DD at night, but we are getting a swing for day sleeps. When DD is in childcare (one day a week) she sleeps in a swing, which is why we decided to look at getting one. Our DD sounds similar to your DS, because she wakes pretty often overnight too, and we basically let her sleep on our laps during the day because any other way she wakes in about 20-30 minutes - hopefully when our swing arrives she will have longer sleeps and DH and I will be able to move around while she's sleeping. I wouldn't worry about the swinging motion; my theory is that if they are sleeping, they are obviously comfortable!