Seats are a funny thing. I really like the seat on the left, and knew it as soon as I started paddling my Whisky 16 Rocker. I did fill in those hollow thigh brace areas underneath by gluing in some foam, so that I could glue a thin pad of foam across the bottom of them. It worked out better than I had imagined for simple and secure thigh braces. That is a really fun kayak for playing in waves.
Now I can relate that slippery seat to my feet not getting tingly. Now I can’t say this is you, but tingly feet is a very common thing among paddlers from simply keeping too much pressure on their feet. Anything that causes people to be a little bit more tense vs a little bit more relaxed, such as directional control issues, tends to make folks keep even more pressure than normal on their feet. My first thought when I read the original post was to suggest that you pay attention to not maintaining constant pressure on your feet. Right after your right blade is planted, you use pressure on your right foot to the extent that it rotates your right hip back a little, and your left hip forward a little. Think about being light against the seat, and using as little pressure as possible to accomplish this movement. If you feel your back pressing against your backrest, this is not useful pressure, and should be eliminated to the best of your ability. Right after that quick twist and stroke, the pressure is off of your right foot, and completely off of it as you put pressure on your left foot after your left blade is completely planted. Now getting these leg muscles involved, even periodically during your paddle in between arm paddling distances, creates increased circulation through these areas. The result you’re going for is increased power that doesn’t feel like you’re working the paddle harder due to smarter and better involvement of different muscles in your strokes. And increased comfort due to eliminating harmful and counterproductive pressure points as well as increased circulation through your lower half. But to keep it simple, you might just practice backing your foot off of the pedal as you’re doing a stroke on the opposite side of the boat.
This is the first thing I would have you think about.