No holy wars please. s/vim/$YOUREDITOR/g
If you're using a LAMP stack mainly (which it seems you are), the option of SSH and using a command line text editor could be of interest.
That being said, if you can create a dev environment that matches your production, why not git around? Where has this workflow failed you previously? Surely also you are developing on multiple servers for different projects, and there are things you do common to all servers?
For my sites I use generally two git repos - one for my toolchain (custom connection, management and setup scripts), one for base content. Given that I use Wordpress for a lot, I can duplicate some of the base work. I use digitalOcean, always a ubuntu 14.04 server, and always set up with the same scripts. I do have a test VM directly on my machine to test things that might seriously break stuff, or for dev when I'm on the go without network, but otherwise, a lot of what I do is "in the cloud" - just over SSH.
As to how this would map to your requirements:
- 1) No syncing hassles across machines
- If you're a team of one, SSH+cli editor should work - it's also lower processing power on your device. Better battery longevity. You can also quickly move back and forth between server logs and code from here too
- 2) No installation of toolchains to get working or back to work — a browser and a connection is all that would be required
- Unless I'm mistaken, you'll always have toolchains to install and update on every new site/server. So long as you maintain an easy way to deploy them fresh, and the new instances you spin up are always predictably similar, I see no problem with maintaining a toolchain deployment recipe in one place, and easily management of instances along the way in teh way you want (ansible, chef, puppet, custom scripts...).
- 3) Easy teamwork
- If the solution you want is for live coolaborative editing, maybe indeed a web-interface which facilitates this may be interesting, though you'll want to check that this mode of "team" working suites your team best, or if revision control-based solution works better for their workflows. Maybe a question for the web-based solution is, does it integrate well with individuals who like to work offline and sync as needed? I'll assume you've already had this talk with them.
- 4) Easy deployment
- I'd say this is down to DRY - Don't Repeat Yourself, or, have you automated everything you could have? :-)
- 5) A move to Chrome OS for ultra-cheap laptop goodness would become realistic.
- That's a personal preference I guess. I wouldn't try it just yet. I try to run a lean machine, but I like to know I Have The Power when I need it.
At the end of the day, so long as you have revision control in whatever solution you choose, you have a decent chance of developing on production. Now about the databases...