I've personally found that potato starch screws up my blood sugar control the way that sugar can, but it doesn't affect my pain levels the way that whole potatoes (or potato flour) can.
It's definitely better than eating french fries, but still not a good choice. There's no way to tell how potato starch will affect you personally. And I share your frustration with trying to find potato, corn, and wheat free foods. I've basically given up on finding any ready-made "gluten free" baked goods. If I occasionally find one I can eat, it's a bonus. Mary's Gone Crackers makes some nice products.