I like your analogies, lapis

To me xingyi seems a nice progression from wing chun, and in addition to being a powerful fighting art, the basics are *so* useful for any other internal method you might like to pick up.

The Chen syllabus is often taught slowly (like, over a decade or more), so you might be able to learn that and another style comfortably, but I think you'll get much more out of a year or two in xingyi if you're willing to wait before moving on to taiji (and indeed you may never want to move!).

Good bagua is a little more difficult to find than good xingyi or good Chen, and I don't know who teaches the yin/yang style in Sydney.