The Chubby 1 I had on loan was just too small...not even the knot itself, but the handle...
For me the Chubby also had less soul, it was a great knot that produced great lather, but just felt boring on the face. The Epsilon has much more character and also a bit more scrub, yet still pillow soft.
Both of them are little hogs, but the Epsilon is large enough, so you still get tons of lather back, while I had to push the Chubby to give enough back for 4 passes.
Sorry, for this horrible comparison, still hope it helps...