Quoted from Glarrownage:
Does anyone know if there are limitations to MPF as you become more familiar with pinball software development?
Well, once you get into complex rulesets and/or states, you need to start writing Python code to cover it. For example, to have bonus countdown lightshows on my EM conversion, I had to write code to handle it (ie. flashing the bonus lamp to turn off, add the 1000 points, repeat). The standard mode-based system isn't really set up for complex if/then conditionals in a traditional way.
Also, it's still an evolving project so sometimes you need to request a feature, but on the plus side the guys are super responsive to the forum and feature requests and turn around is pretty quick. Each release introduces more useful features.
I'll take that list and put up a grid tomorrow, then solicit answers.