I only went co-ed. I had a brother and sister at the same school. There are plenty of studies out there (plenty!) about the benefits of single sex or co-ed.
Personally i only have my experience to go on, and i loved my school and it seemed normal to have guys and girls together. I honestly didn't find it distracting.

Do teachers in single sex schools actually use different teaching methods - or does the different teaching environment stem solely from the absence of the opposite gender?