I can give you some pros and cons of the NC year round schools, but not for St. Mary's. Although, I am sure the results will be very similar.
Alot of people in NC were against year round schools when the idea was first passed. But in the years that have followed more parents have warmed to the idea and are putting their children in year round schools. It is a firm belief among parents in NC that children seem to forget what they have learned over the summer and therefore spend more time refreshing their memories when the new school year starts. I don't think the statistics are a fair assessment of the difference in acheivement because the traditional schools that still exist tend to be magnet schools which receive alot more federal funding for programs such as ELS, Title I and ASP. ASP is a summer program for low to moderate performing children, so basically they are going year round also.
Most of the new schools built in the county we lived in are year round schools and they fill up fast. Parents still have a choice as to which type of school to send their children too. You may have to provide transportation, but you can send them to traditional school if you want.
One con to year round is finding child care for the three week breaks every nine months. Summer programs and after school programs tend to still run on the traditional calendar schedule.