I was wondering, if the goal is to be able to note 1-10 sensations a second and eventually work up to 40+/second, is it necessary to cycle through multiple different sensations per second, or can I just crank up my metronome to 600bpm and focus solely on that? 

Might be more useful and realistic to use your own heartbeat as the metronome, if you even need it. The super-fast stuff likely won't even be noticeable to you without massive strength in concentration, so try not to get too caught up in those descriptions.

That said, there's something hilarious about the idea of doing "Venetian Snares"-influenced vipassana.

Wouldn't recommend it (perhaps just the first couple of minutes?). Heartbeat is not a wise choice, you could hurt yourself. For A&P, 12-20 bps would be just fine.