I have both as well. I love my Peanut but I LOVE my beagle. I'll never part with either but I find the Beagle going in my pocket much more than the Peanut.
The Beagle has more differentiated blades and I love the little coping. The Beagle is able to easily be used as an only knife (like a larger knife is) while I find the Peanut a bit too small in my hands to really cut something like thick cardboard with.
My family loves the Beagle: