I've used IntelliJ for a decade (including several hours today) and it's never very seamless. The sync features are hit or miss, especially across platforms -- I've used it on various Windowses, Linuxes, and macOS. The hotkeys aren't the same, the interpreters aren't the same, the containers (Docker or Python) don't function the same, the linters don't present the same, the NPM modules don't always compile on different architectures (sigh, M1), the memory settings don't always persist, some are synced to Jetbrains and others are stored per-repo... it's a nightmare to untangle. The syncing is there, sort of, but it's far from seamless. There is still a lot of complexity and points of failure between the bare metal and my code (whether it's PHP or Python or Javascript). And if you can't afford IntelliJ ultimate and use separate products (like PyCharm and PHPStorm), the integrations are even worse, along with trying to figure out which product offers which feature (like Javascript support, or SQL).
What I'm hoping for is an easily reproducible dev environments with common-sense images that can be maintained and edited in the cloud, almost like Docker images, with all that stuff preconfigured... the latest interpreters, node, yarn, xdebug, webpack, blah blah all just preconfigured and ready to go. Next.js does some of that, the dev tool Lando tries to do that (but is pretty buggy), but all of it still requires a lot of manual configuration. And coding across platforms (like Windows desktop + Mac laptop) is still a huge PITA even though it all gets deployed to bog-standard LEMP stacks in the end.
It's just such a far cry from, say, being able to seamlessly use the Adobe Suite or Slack or Zoom or Microsoft Office across platforms and projects. I guess it's a bit unfair to compare first-party vendor software to messy open-source ecosystems, but that's what I'm ultimately griping about... I don't want to spend time doing devops instead of coding visitor-facing features. Some companies have dedicated people for that; our org can't afford that, so I just have to figure it out as I go, doing a piss-poor job most of the time. Wish there was a vendor + service to take care of that, and present just a usable IDE in the end, with all the internals abstracted away and maintained in the cloud. Ideally it would be a thin local client with native GUI but offloaded processing, vs a laggy screenshare.
I haven't tried Cloud9 in particular but have tried other cloud IDEs, which just felt like remote desktops running on someone else's machine that I still have to do all the same tooling and maintenance for myself. If Cloud9 or others DOES do what I want and I just missed it, please let me know.
shrug Maybe I'm just getting too old for this stuff. I miss the simple jQuery days when there was the DOM and that was it, not a bazillion layers of tooling and the super complex packagers and containers and other enterprise tech required to support them.