You might want to start by asking Hoomaluo Labs what safety testing they’ve done. It’s hard to be sure from a photo but those incoming phase lines look a bit close for something that’s going to have 415V across it. If arcing were to break out there it could get pretty exciting.
And I’m pretty sure if you were coding it up as per that photo above when the Neutral went away, your laptop would be at mains voltage. You really need the isolation in place while you’re doing the development.
Not something I have any experience with, but my gut feel is that shouldn’t be an issue. It’s all user level code (apart from a bit of SPI driver kernel code) running on a general purpose computer with a general purpose OS. If things get busy the scheduler will do its stuff and all the processes will just run a bit slower, but I’d be amazed if you can even notice the odd SPI transaction on emoncms performance. Even if you were to code it with lots of busy wait loops, you can just ‘nice’ your process to a lower priority than Apache - not that you should as that would make your RPi run hotter.
No, when I say “our ADE based monitor” I should have said “my ADE based monitor” but that would have excluded my collaborator. It’s not related to OEM, and is neither open nor commercial. There’s a pic of it here.