My MIL has a J10, and my DH has a z20. We use the z20 for auction photos & my DH letters trucks so he uses it to take pics of trucks for color reference & after they are lettered. For those 2 purposes it is great. Small, compact, lightweight, easy to always have on hand.....BUT, both of these models have terrible shutter lag, and are IMO completely useless for shooting moving people.
I took my MILs camera to church for the last day performance of vacation bible school. I took 25 pictures, and not one of them is worth keeping. In every shot, my DD moved before I could capture the facial expression I shot for. Same with my DH's camera at a party we went to. Outdoors, kids jumping & sliding on inflatables, not a single shot came out right.
Now, the more expensive model you are looking at may be better...but knowing what I know, I would caution you to try before you buy! We bought DH's camera at circuit city & I was trying to steer my DH to a canon instead, but the salesperson convinced him this camera was superior.
Good Luck!