The question of rise and fall could be answered by attending a milonga in Lo de Celia or Centro Region Leonesa and observing the milongueros. If you can't make the trip in person, watch a video on YouTube.
With respect, no, the question of rise and fall - or any other question for that matter - cannot be answered by watching youtube records of people dancing in BsAs. I am sorry but it's a myth that ALL Argentinians are perfect dancers. It was the shock of my life when on my first visit to BA I had a dance with an elderly porteno, who was not musical at all, whose lead was rough, who held me so tight I could not breathe, who knocked me off balance all the time. This happened at the Lo de Celia, with no obvious tourist in the crowd apart from me. There were other similar incidents, especially at non-touristy milongas. In fact, at a milonga in the Grisel I had such a bad run of dances with 'milongueros' - they all look the part, mind you, - that I left early, very despirited. Travelling thousands of miles for that?!! Sure, a majority of dances i had in BA with milongueros were divine. But about 20 per cent were crap.
To put things in context: I've been to BsAs five times, I went to milongas every day, both touristy and non-touristy.
Back to Jan's advice above: if we just watch uncritically people dancing in BA milongas, how do we know who to take as an example? Some of them seem to change height, some don't.
As for me, I'm with Peaches: don't bounce. Beyond that, do whatever works and looks elegant.