I'm glad you posted this thread. It has started a good discussion on different types of set ups depending on people's different needs and opinions. I'm not sure if I've seen this topic discussed before so I'll plan on saving this thread for future reference.
I for one actually like a dual battery set up. If using lead acid batteries you're only adding about 20 pounds and is not a big deal. If you use lithium-ion batteries, you're only adding about six or seven extra pounds which is really no problem. Also, the extra battery gives me more time for running the winch or more time running the radio when the engine is not running. Another benefit is, if you have a place to store the extra battery under the seat or under the front hood then you don't lose cargo space on the vehicle.
Your Stanley Pak has a built in compressor and inverter though so that's nice. Right now I am carrying a small compressor that is a standalone unit. So, if I want to carry a jump starter, I will have two items instead of an all in one like yours.
Thanks again, this is interesting stuff and I may have to add a jump starter to my inventory sometime.