[LAD] platform choices, jack for sequencing?

Thanks everyone for all the help on my architecture questions. It seems like a lot of the best practise functionality has tools/components for it already in Jack. I *was* planning on using rtaudio in order to be cross platform, but if it's a lot easier to get things done in Jack, i could live with being limited to linux and OS X. Just wondered if I could poll opinions, for a real time step sequencer meant to do super tight timing and by syncable with other apps, is Jack going to be a lot easier to work with? Should I just lay into the jack tutorials? And is it straightforward to use the perry cook stk in a jack app? thanks everyone iain