That looks like a pretty darned good hill. This close to the actual ride it may not make a big difference in your overall fitness, but it'll definitely prepare you mentally for a lot of what you'll see on the pie Ride. I'm pretty sure Palomar averages around 7.5%.
Just remember: Climbing is one thing, but for a lof of people, the descending is the most difficult aspect rides like these. So if you aren't used to riding up and down mountains, be CAREFUL.
What is your longest ride to date, anyway?
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"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return." - Leonardo daVinci