Another PFD Question

I am in the process of ordering my first kayak, a SOT Malibu Mini-X. I will also be ordering a Atec 1 seat with it. My question relates to the selection of a pfd: Do I want a full length type jacket, or one that has a short back…?? I presently have a bass boat type pfd with a collar and 3 buckles across the front. Is something like this practical…?? Suggestions and comments appreciated.

Go for backless
Stohlquist A-Sea, Lotus Mildwater, or Astral will be much more comfortable with a seat back.