hmm. intersting. I havent swapped the fins on the skillet over yet, but will be interesting to see how it goes. I've been riding a 5'4" x 21 1/2 quad with standard FCS M5/G1000 rears and find that comfortable. (same board/setup that i paddle surf). I used to ride a 6'3" thruster and found it paddle surfed well with M7s (larger fins) and kited better with the M5s (i'm 85kgs). I liked the smaller M5s for kiting because it made the board feel looser. Was too locked in on the larger M7s, but enjoyed them paddle surfing because they drew out my turns and gave me a bit more to drive off.
Horses for courses i guess. I learn't to tack on a raceboard, so different game altogether. Takes time. I found tacks you can really slow it all down, bring the kite up slow and use it to support your weight and then flick the board around underneath you. Gybing was the opposite. Speed is your friend, if you keep the board planning through it, it is much more stable then coming off the plane and sinking down.
Beg, burrow or steal some smaller fins and see how it goes. Fins are one of those things, doesn't hurt to have a spare set in the bag anyway as it may save a session when one gets damaged, lost or stolen by someone else trying to figure out which setup works best