Right now the MS-I processor has more than enough cycles to handle everything you can do with extra code. The only time I find where the processor runs out of cycles is when burning a new map. Not always, but sometimes you will get a stumble or two when loading a new map.
Now if MS-II could do full sequential fuel and spark, and your project had a redline of 12K RPM, you could use the additional processing speed. But where the MS-II extra does most everything that MS-I extra does, there really isn't a need. Even with large injectors and small opening times, it is not the processor that can't keep up, it is the injectors.