I am in the exact same boat. My contract is due to expire and my old M7 has the well known purple haze issue (quality control / heat problem). I was all set to get the Note 4 but now this! Exactly the pros and cons you list are on my own mind, and I'm really wanting the bigger screen as I'm 6'5" with big hands and I consume a lot of media on my phone.
As you say the S6 has a better SoC and faster RAM, not to mention way faster UFS2 memory. That then leads me down the mental path of 'Well in that case the Note 5 is due at the end of the year and should have the best of both...' route, but then that means waiting with a broken camera phone and a brand new baby begging to be photographed lol
I might go S6 for now and then sell it to use the cash toward a Note 5 later. I hate choosing.