I'm certain that every child and school district responds differently to half/full kindergarten. In our district, the teachers feel more pressure in the half-day classes to keep the kids on track and prepare them for 1st grade. I'm attaching an article that I think will help you.
I personally feel that a full day of Kindergarten is best. Kindergarten is a time to prepare them for primary grades and you can't get that idea from being pampered and attending only 1/2 of a day. Kindergarten is just as important as 1st grade (maybe more) they are taught so many skills that is essential to success in the following years.
To my experience, 1/2 day Kindergarten is ONLY available in states that don't yet require Kindergarten as part of the elementary experience.
Many states, including mine, require Kindergarten and it is treated in the same manner as 1st grade.