Only you can decide if the extra weight is worth it! They're both great packs, carry well, and I'm in love with the ULA hip belt!
I'd point out that the Ciruit's top closes with a fold-over, which protects from rain better than the Ohm's simple drawstring. I don't know if that would be a factor for you.
I've made one tweak to the Ohm to make it so I don't have to worry so much about careful packing, i.e., sharp objects poking into my back. I took a hard plastic back insert from an old daypack, trimmed it and glued it to the thin foam sheet in the Ohm's back. This was a nice improvement, and added only a couple of ounces. I suspect that if you called ULA, they would be willing to do something similar for you. They don't need to glue it for you (in fact, don't ask them to - you can do your won experimenting with and without), because a bit of silicone will glue it easily.