I'm looking at getting an electronic collar for pepper. I would like to let her run around the whole acre I have, but her instinct is just too strong. There are cats and squirrels everywhere. There's a busy street right on the other side of the house, too. I want to let her off leash, because she's so good when walking with distractions. I know part of it is that I panic when she bolts and I can't be assertive when I'm panicking.

What do you guys think? would a rattie do well with something like this, or would they be too strong willed for it?

I am assuming you are talking about an e-collar, (some people call them shock collars).
PLEASE do not use one of these without getting someone who has experience with them to show you how to use it. You can break a dog's spirit very easily if you don't know how to do it correctly. It's NOT just a matter of putting the collar on the dog... and then when the dog starts running you hit a button to stop him. It doesn't work that way. The dog needs to have some basics down pat and must know what the "come" command means... otherwise to use an e-collar on the dog would NOT be fair to the dog.
I'm not against them... I had to use one with Bailey.... and now (a year and a half later) I would put his recall up against the recall of  just about any dog I've trained. 
I've obedience-trained dogs for 10 years but had never used an e-collar before. So I had a friend who is a professional police dog trainer... do several sessions with me and Bailey with the e-collar. It's very effective if done correctly.
Please do it correctly if you do it... I would hate to see you "break" Pepper's spirit.