Gadrocs own firmware is available for the Arduino platform. So why re-invent the wheel for the MSP430 controllers?
Here is a brief comparison of the MSP430 and Arduino platforms regarding building custom hardware for Helios (so this will ignore aspects like power consumption, which is mostly irrelevant for non-battery powered applications).
Please note that while I have experience with Atmel AVR microcontrollers, I have only read about the Arduino platform – I have not used the Arduino IDE myself yet.
The MSP430 Value Line controllers are cheaper than the higher-end ATMega controllers used in the Arduino platform.
You don’t need an external crystal, because the MSP430 controllers can run at the full 16 Mhz from their internal clock source.
With the MSP430 Launchpad, TI offers a development board that includes everything you need for about a quarter of the cost of an Arduino board:
A programmer for the MSP430 controllers
comes with two microcontrollers (a MSP430G2553 and a MSP430G2452)
in addition to connecting the programmer, the USB connection also allows you to talk to the microcontroller via a serial connection at 9600 baud, so you don’t need a separate “FTDI cable”.
The Arduino works with 5V logic levels, so you can directly connect it with other 5V logic such as some LCD character displays. The MSP430 requires a supply voltage of 1.8V to 3.6V, so if you want to interface with 5V logic (such as some LCD character displays), you may need a level shifter. The MSP430 Launchpad will supply 3.6V to the controller, so if you want to connect to 3.3V logic, you may need to use another power source.
Note that driving the common HD44780 based LCD displays should work without a level shifter because (at least according to the first datasheet I found) the controller will read anything above 2.2V as logic high. (You can power your 5V LCD directly from USB – on the Launchpad, look for the two test pads labelled “TP3” and “TP1” next to the USB connector.)
The Arduino has a larger community focused on beginners. Given the amount and quality of documentation on the web, both platforms should be suitable for absolute beginners, though.
Atmels AVR controllers have been around for a long time. Combined with the popularity of the Arduino platform, this means that they are available from a huge number of sources. MSP430 controllers are hard to find outside of TI resellers, so you have fewer options (see also: Buying MSP430 controllers).