It's not that stiff of a board, so I wouldn't get bindings like the diode. From your list, the cartel would be a good option. I ran mine with the NOW IPO last year and loved the combo. From what you're describing though, with toe edge pressure, a stiffer highback is not going to help that. I'm thinking you need to look into your boots, whether it's a different pair or how you set them up.
14 NeverSummer Prospector Splitboard . 14 NeverSummer Proto HD . 13 NeverSummer Cobra . 13 Gnu Space Case EC2PTX. 11 Nitro Team Gullwing
14 Now Drive . 13 Now IPO . 13 Salomon Hologram
14 Flow Hylite . 13 32 Binary