You are right. The HD Rumble makes the sound of the coin. You can clearly hear it if you mute your tv or whatever.
Is it like the swoosh sound captured here?
Yup, it's cool! ^^
People shouldn't expect a reinvention of the wheel, though. It's an evolution of regular rumble, nothing more, but also nothing less. It definitely feels better.
Argghh, just one more week till I am back with my Switchy
The game I'd really look out for is ARMS.
I hope they deliver a nice springy feel when using the joy con to deliver certain punches + rumble for telling where you've been hit and if your block is successful.
Apart from that the only game I'd figure will use it to any interesting impact would be Mario Odyssey
ARMS might have it, just don't know how effective they'll be when you are moving your own arms around. Like I mentioned in the OP I did not notice if the fighting minigames had or not HD rumble. Would expect the same thing to happen with ARMS.