I love surface metal-lips. I fish them a lot, and I know that probably puts me in some small minority. They really vibe with where I fish, and my style. And it doesn't hurt that my personal best is on a Danny!
I have fished them in just about every condition you can think of, but do concede they work best in calmer conditions, and in places that aren't super deep.
However, they are phenomenally effective in a variety of places, and if you aren't using them, you're missing out. I urge you to consider what I'm saying here, and try out a couple of the less expensive options to get your feet wet. Then, if you like them, jump in with some more expensive plugs. There are few plugs I can think of that provide as big a profile (sound, vibration, and visual) as a Danny or Pikie!