It appears that there are several strengths of the newer x7x parts over an existing 28335, including faster flash speed, on chip oscillators, hardware accelerators, additional communications options. It also looks like there have been improvements made to the ADC, PWM.
What about low power modes? I know that C2000 is not necessarily the "low power leader," but it appears that there are some enhancements that have been made in this area. How much has it improved the part?