Our April issue themed "Amplifiers and Oscillators" just came out with the lead story about the advantages and disadvantages of Si versus GaAs based semiconductor technologies for power amplifier applications (the discussion is contained to lower power levels, <1 W where they both have good performance). It discusses how Si has made many strides in this arena and could be the preferred technology for many applications.
There is no doubt that GaAs is usually better suited for higher power applications but in the high power realm, LDMOS (at lower frequencies) and GaN have made significant inroads into the market. So it seems GaAs is always getting squeezed in the market with competition on both ends. We will address this high power market in our June issue lead story as LDMOS and GaN face off. Please read the article and let us know your feedback - I am sure the GaAs proponents will have something to say!