If the Showdown's were $200, I would definitely consider buying one, but when you have to spend $350-$400 for one, I would go with ANY brand of flasher over the Showdown. It does take a couple hours to really get used to what you're looking at on a flasher, but once you figure it out, you will LOVE the flasher.
I've personally never used a Showdown...but have talked to many guys that have, and several of them then went to a flasher, and I don't think anyone has gone back to the Showdown.
I bought the Marcum LX5 2 years ago when it was $400...and it is well worth every penny!