Hi,
there is a reason why you have Keil for 8051 and IAR for the MSP 430 and that is because they are the best for these two processors. IAR clearly leads the pack of the few 430 compilers out there and Keil has probably far more than 50% of the professional 51 compiler market. So if you are looking into a hobby project, go and look for free compilers, if you are a professional user with tough time to market needs, you already found the two compilers you should use.
Bob