Regardless of who has the most processing power, it's the algorithm that matters.

For example, Lexicon released PCM as a hardware unit, and than as native plugins. They state that the plugins have a smaller buffer, but the algorithms are identical, and according to some tests, they sound identical.

There is no "magic" about hardware units; they're just more expensive (ADC/DAC, actual hardware, dedicated DSP chips, manufacturing) and the guys making them can afford to work more on research and development. Also, the hardware guys have been doing this for a longer time than the software guys, so they have more experience.


Also, I have limited experience with Alchemy, but pick both, if you can.