We considered something similar to this, but we planned to align the tiers based upon our internal classifications (ie: Executives 70%, Salaried Exempt 75% ). We were modeling an extreme, and the math works out that 70% is the lowest we could go for exempt workers without dipping below the $684 threshold for exempt status.
We also had some discussions around what meets the 'bona fide" criteria listed in #7 from the WHD/DOL fact Sheet #70
After much discussion, we have not made any reductions at this point. An (unconfirmed) news article listed a local company plan to cut Exec's to 40% and remaining Salaried Exempt to 50% for the month of April.