For reloading the current preset: Like many folks I think, the switches on my presets layout also load my scenes layout, so that's usually where I am when I've modified a preset I want to reload. That has a switch to go to my presets layout, so I just hit that, then the lit up switch for the current preset.
No it's not one button push away, it's two, not a big deal to me. It's also not something I need that often, except when I've been editing and don't like where I've ended up, in which case I'm not in a super hurry and two stomps is ok, or the AxeEdit key combo for Revert.