I much prefer a Reunion to a hard case. They hold the bass better in most instances, and weigh less than most. As far as hybrid bags go the Reunion, Mono, and Contego are most well known IMO. Below is my experience with those three; may have gone overboard.
I had the Reunion Blue and the Mono M80 at the same time. I compared them apples to apples and ended up keeping the Reunion. The reunion was slightly deeper, front to back, than the M80 which is what I'd consider "bulk". It had comparable pocket space with a slight edge going to the Mono. But in the end it was the durability and safety of the Reunion that sold me. Those things are solid. The Reunion just feels much more protective than the M80. I thought that its added "bulk" was not more than an inch or so and made a huge difference in stability.
Not to bandwagon, but I am also a big fan of the Contego, maybe my favorite all time, but sold it with a guitar that it came with. I did not mention it compared to the Reunion above because I did not have them at the same time. I can say that the Contego feels more solid, less pliable, than the Mono. Felt like the Reunion in that way.
My only complaint about the reunion is that the strap height is low on the case, so when its on my back I can't walk through doorways without getting hung up on the top. I don't remember how the Contego or M80 were in that aspect. That can be really annoying when trying to load in with a couple cabs and your bass, only to reach a doorway and have to put everything down, walk in, and start over.
**EDIT** Just fyi, I looked up the specs on the M80 and the Reunion.
Reunion: 9 lb, 7" deep
M80: 5 3/4 lb, 6.5" deep