Climbs and such can't be trusted when you are using any internet referenced mapping source, only your eyes will tell you the truth.
An example is well deserved to show what I'm talking about.
(unnamed) - Franklin County, KY
I rode this climb back this summer. I was expecting a real butt kicker climb. I downshifted to a 30x15 and ended up climbing this thing like it was nothing. I rode 11 mph up the entire climb. Oh yeah, to make matters worse, where the map shows the first drop occurs(just under 200 foot drop) there is no drop. It's a solid climb straight up the top. The map data sucks. I wouldn't even come close to calling this a 15-18% grade climb by a long shot, maybe 12% pushing it.
Now to make matters even worse I got up top of the hill and stopped in the convenience store and saw the Frankfort newspaper was saying the route I planning to take as I pedaled away from the capitol building was about to close...50 minutes later. I got into Frankfort and made my way to the capitol building and after going around the capitol I started to leave and saw the closed sign and also saw the road I had been planning on heading back up to the highway on...a nice steep climb. I thought...sweet, I'll avoid that climb. I had a road straight in front of me and decided to take it hoping it would angle me up at a shallower angle and allow me to cut back to the original route. The original plan was to take Lafayette Drive. That climbed I would guess is 18%+ grade.
(unnamed) - Frankfort, KY
I took Shelby St and had a decent 10-12% climb up the first part before the 90 degree bend. There was a bit of break, as I remember, right near the curve in the road and I downshifted to the 30x15 and as I got around the curve I saw the steepest road I have ever seen to date. I was glad I was riding in that low of a gear and was only making 4 mph up the hill. It was easily over 20% grade. The map data makes you want to believe it's only 12% and that it isn't as steep as the climb north of Frankfort that I saw an hour or so earlier.
The map data was horribly flawed. Heck I even saw bad mileage data both around Nashville and New Orleans this summer. You can't trust the map data and especially the way it wants to calculate the % grade.
I just know a climb is coming and don't worry too much about how it compares to another climb. The way you feel at the time in question can make a big difference between and easy climb and a climb that is utterly miserable. Trying to compare one hill to the next can only be done at the time in question and I wouldn't waste my time trying to do it without being there/riding it.