I took CUHK's full-time Cantonese 1 course last semester, This semester I'm taking the part-time Saturday course, and taking one day a week of the full-time course to work on reading and writing.
Pros of last semester's course: you'll learn a ton. excellent job of teaching vocab, usage, accent/tones. it's a very well-thought out curriculum.
maybe pro/maybe con: you won't learn to read or write in the first semester.
Con: it's your life. 3 hours a day, plus whatever commute you have. plus an hour or so of homework per day (more if you really want to remember everything). and when you're all done, it's not like you're fluent or anything. i've learned a ton but stil can't say/understand most things.
The part-time classes are another option if you think that you're getting a lot of access to Cantonese otherwise, but they won't come close to what you'll learn if you take the full plunge.
I don't know anything about the HKU classes.