Slimful Bar Chews
 

Has anyone tried these and what is your experience with them?

Based on the ingredients, you are better off just buying a regular fiber supplement. They are basically sugar bars with fiber added:

Ingredients: Corn Syrup, Sugar, Maltodextrin, Cocoa Powder (Processed with Alkali), Konjac flour, Fractionated Palm Kernal Oil, Soy Protein Isolate, Glycerine, Natural and Artificial Flavor, Agar, Locust Bean Gum, Xanthan Gum, Carrageenan, Chocolate Liquor, Salt, Soy Lecithin.

I'd definitely skip.