You are faced with a question many parents consider.  Starting a child a year later is common, and I personally don’t consider it “being held back.”  As you expressed, each state has its own date for when each child should start kindergarten.  While your daughter misses the Florida cut off by less than a month, you need to consider whether you would want her to miss the Connecticut cut off by half a year.  
Besides thinking about the move, you can also consider the following: is there a benefit in pushing her ahead to kindergarten?  Is there a benefit in giving her an extra year to mature?   Perhaps you can think about what decision would help her most come 10 or even 20 years down the road.  
 
Here an article from the U.S. Department of Education, “He Has a Summer Birthday: The Kindergarten Entrance Age Dilemma”:
http://www.education.com/reference/article/Ref_He_Has_Summer/
 
This decision is ultimately yours, since you know your daughter best.  Consulting her preschool teachers can also give you an insight to how she interacts with other children in a classroom environment.  Keep in mind that research shows that children who are older in their grade are more developmentally ready to succeed both socially and academically.  
 
I would personally advise you to give your daughter the gift of another year of slapping paint on easels and playing with blocks in preschool.  Being more mature and older in one’s grade is definitely more beneficial than being younger and less ready.  Age is inconsequential in the real world.   Maturity, adeptness, and aptitude are important.

Typically, girls mature faster than boys.  As an educator, I do not often recommend holding girls back.  Boys, due to their immaturity (sorry moms of boys!), are often recommended for retention either before or after the Kindergarten year.  If your daughter is doing academically well, then why hold her back?  You can always retain her after Kindergarten if your concerns prove valid. There are other August birthday children in the same situation as your daughter.  Your concern for her academic education should be your primary concern. Northern schools have the reputation for being more challenging than in the south. (Sorry, Southerners!)  That said, your move and her reaction to the move, should also be taken into account before you make any decisions.  If you retain her, you get to enjoy another year with your daughter and explore your new surroundings together.  Know that whatever you choose to do will be the right decision for you and our daughter.