I noticed this - https://ccs.ti.com/
It's in public beta right now. It's a Node.js-based lightweight version of the CCS IDE without debugging features (just code flashing). Supports importing Energia projects (although without debugging it doesn't really offer anything above the Energia IDE), presently only supports MSP430 chips, and its flashing subsystem supports the MSP-EXP430G2 FET, eZFET and possibly MSP-FET, FET430UIF, etc.
I played around with it a bit, just getting a blinky program running on my F5529LP. The flashing subsystem requires a new piece of software called "TI Cloud Agent" which is provided for download when you go to the "Target > Connect COM port" menu option. I ran it under Fedora 19 Linux 64-bit and it works. The Cloud Agent is a downloadable binary you run which provides a lightweight installer, runs some scripts as root (or requests that you do it manually) and installs itself in $HOME/TICloudAgent.
Then there's a Chrome extension you install which allows the IDE to talk with the Cloud Agent. (This Chrome extension should automatically start the Cloud Agent processes for you, i.e. no need to start them on bootup)
I have chatted with the support team (ticloudtools@list.ti.com) a bit and found out a few details-
1. MSP430 projects (non-Energia imported sketches) use CL430 *non-code-size-limited*!
2. All MSP430 chips supported by CCS6 should be available for use here. Since it uses the standard MSP Debug Stack for its flashing I assume you could, e.g., use it with an MSP-FET or MSP-FET430UIF and target board, such as the PZ100USB (F5659) or the one used for the FR6989 giveaway.
3. No support for "switching compilers" at the moment. The Energia sketch support uses Energia's build of mspgcc internally. I don't believe it requires Energia to be installed locally.
4. Energia sketches require you specify the arch and board when they're created, but I don't see any way of "changing" the intended board. Have to create a new project to make a sketch for a different MSP430 launchpad board.