Has anyone tried these? They're cheaper than the entry-model gold flutes of other companies. Also, are Muramatsu headjoints good?

Why do you want an "entry level" solid gold flute? What are you playing now?

Currently playing on a silver Powell. I'm going to sell this and get a new flute and put a different head on it, probably.

Never played one, and undoubtededly out of my depth even if I had, but I love my Muramatsu ex. As of 2004, James Galway loved Muramatsu, though he has since switched to Nagahara. He has a video of himself playing a number of different flutes, including the 9k: http://www.jennifercluff.com/fluteloops09.htm

Why do you think a 9K Muramatsu will be an upgrade from a Powell?

If you look at the video of Galway playing all of those flutes, the Muramatsu EX sounded the same as most of the others other than a slight variation in overall color. ie - quality was the same, or so close that it appears to have made almost no difference. Your Powell body is already at a level where it's as good as flutes can get.

What will make a difference is the headjoint. You can save a ton of money over a whole new flute and get a better sound by replacing the stock Powell headjoint for something else.