Trader Joe's has a great Oatmeal Exfoliant bar called "Savon de France" fragranced with Ginger Almond. This big white bar has a small amount of the big flakes, which I can tolerate just fine.
If I need super scratchy soap I'd use finely ground apricot kernels or even softer seeds.
You should try this soap from LUSH:
http://www.lushusa.com/shop/products/ba ... p/porridgeWhile the smell is great, the oats used in this soap are relatively SOFT. Dunno why... but this soap is like 90% exfoliating and 10% soap.
I can however tolerate the high amount of oats in this bar. Probably because they are ROUND and not flat...

I think I just had an epiphany:
oatmeal flakes = flat scratchy feel (sometimes uneven)
Uncut oats = softer "kernels", almost feel like tiny beads
A coarsely ground mixture might be a best bet if you're looking for an evenly distributed exfoliant.