You are right on
Putts break more since when they are going downhill they are moving slower, than if you had the same distance for an uphill putt. Since they are moving slower then gravity has more time to act on the ball and moves it more… causing a greater break. For example, if you think about a clock around the hole, with 12 being the straight downhill putt, then a ball at 1 pm would break more than one at 5 p.m. even though the are both 1 off the straight putt (with 6 being the straight uphill putt). I hope my explanation makes sense.
Here is a real life example, … I pulled this from an AimChart which was used in the original version of Aimpoint before it was made simpler with Aimpoint Express. Given a STIMP of 11. A 20 foot downhill putt on a green location with 2% slope from the 1 o’clock position will break 17 inches, while a 20 foot uphill putt from the 5 o’clock position will break 9 inches.