Sailed NJ, a friend of mine has 2 jack russels and a 3 year old kid at home. Needless to say, when i go to his condo, it looks like they're all on way too much caffiene. lol and it doesn't stop ! I think a JR is a little too energetic for us.
I have a Jack Russel/Yorkie mix ("Jorkie") and while they certainly have a tendency to be hyper at times, it isn't ALL the time...just 98% of the time...

But they are great dogs. Smart, easy to train, and will absolutely love being outside whenever you give them the chance. I push her around all the time and they love "fighting back." Most playful dog I have ever had, but they will tire out eventually LOL.
Just my 2 cents.