Cutting out grains isn't just about the gluten, but about the starch and sugar too. Replacing grains with fruit and potatoes is likely not optimal.

I've been eating paleo/primal/low-carb (whatever) for half a year now. The need/craving for sweets and carby stuff disappears in a week (for me, YMMV). I eat about the same as I used to (which means I'm eating more meat and veggies to compensate) and don't recognize the hunger aspect of it at all. What I like most is the complete lack of insulin surge after a meal. I can eat a meal and immediatelly go sporting, because there is no insulin spike and thus no energy dip.

However, each body reacts differently, and it might now work for you. I know some people stay hungry without noticing anything.