Jam2 and ULACircuit

Anyone got a Jam2 and a circuit. I have a Jam2 and love it. A tiny bit more room would be nice for winter use and more extended trips. I was looking at the ULA Circuit. Is the main body of these packs similar in size. I am better at physical shopping for items like this so any input will help. I have been studying Brians little photos of the circuit, but that aint the same as hands on. Thanks.