[Mini Me]

First of all, training collars are not bad, you just need to be aware of how you use them. I'm sure you know that already. ;-) Your girl sounds like she's getting it, just let her progress at the pace which your time allows. They're only as good as your effort and consistency.

If your goal is to work with a flat collar though, then work with a flat collar. I switched my guy to a slip collar when we started our novice obedience, having done puppy class in a flat one. It did help, but I'm not entirely convinced that it's any more effective than I am when I really get into it. The absolute fastest way to get my guy's attention is for me to go crazy with the high happy, 'this is SOOO exciting' voice.

We always talk here about setting our dogs up to fail. Maybe you need to take your attention work a little slower when you're out in the real world. Get her really solid in mildy distracting environments, and be very aware of her progress when you start upping the distraction levels.

I would (and do) keep a slip collar in my arsenal for times when I can't afford to be anything other than completely in control. We train in it because that's how he was taught, and when we go somewhere really exciting, but I do as many of our walks in the flat collar as the slip.

Hope my experience is helpful. Knowing this board, you should have a few very informative answers soon.