Heres some fun with numbers:
On the ORCA Card (in Seattle), It is $9 for every 25¢ increase in fare, or $1.80 per 5¢.
Lets break down TriMets fare, Assuming 365 days per year - 104 weekend days - 6 holidays = 255 average commute days per year:
$77 X 12 = $924 / 255 = $3.62 /2 = $1.81 per trip (assumes one round trip per day, 2-zone pass)
$81 X 12 = $972 / 255 = $3.81 /2 = $1.91 per trip, a 9¢ increase per trip.
Either way you look at it, someone up at TriMet is rewarding cash riders, as the value of the Monthly pass is diminishing. A monthly pass holder is saving 24¢ right now per ride, or $10.20 per month, at the new rate, Pass holders will save 19¢ per trip, or $8.07 per month.
It should be a $2 increase, to realize the fair amount of savings, period.