I have a clearvue 5hp DC and a harbor freight 2 hp dc, both are incredibly loud. I've had to build a closet around the clearvue to dampen the noise, but it's still loud enough to be heard from across the neighborhood.
I can't speak to the grizzly, but 70-72 db is is the same rating as my 'quiet' vacuum cleaner, I doubt any dust collector that actually sucks is so quiet. Would it be possible for you to get a demo of the machine?
If noise is a concern, I'd recommend a closet with sound dampening material or doubled sheetrock to muffle the noise.