There's no reason to buy an ESC because it has a 32-bit processor. 32-bits just means it can process data 32-bits at a time versus 16 or 8bits. There's a lot that goes into the algorithms on the new ESCs and no one but the developers would really know if there is any kind of benefit, or if they are limited by data processing speeds. In addition the actual clock speed of the processor also comes into play when doing the necessary calculations and processing of the data. In other words you can have a 32-bit processor running 1/2 the speed of a 16bit processor and be slower. Another thing that factors into the efficiency of performing the algorithms and data processing would be the actual assembly instructions of the processor. Some processors specialize in specific areas and optimize for specific situations (DSPs for example).

I'll quit blabbing now, and re-iterate that I wouldn't buy an ESC based on processor being 32-bit.