My duet partner plays a Haynes - closed hole, Cooper scale perhaps 20 years old. It's very similar to my bone stock Jupiter 711 in sound and playability. Same scale, very similar headjoint and response. That's not to say the 711 is a bad flute... it's just that the Haynes is considered a totally different league, but nobody in the audience would ever hear the difference.
I'm not a big fan of the Powell sound either. It's a good sound for those who like that sort of sound, just not for me. The sound that floats my boat is the Lunn that one of the players in our flute choir and Sinfonia plays. That is an incredible sound, but she would sound great no matter what she played. That is, what I really like is not her flute, but her sound.
And that gets to the kernel of it. Seems to me that when you peel off all expectations, image, price, reputation whatever and get down to the brass tacks of how the flute plays and sounds, the differences are much smaller. For example this Lunn is the best example I have ever seen of ultimate hand craftsmanship and build quality, a beautiful playing and sounding flute. But how much different does it actually play and sound compared to a factory flute that cost 1/6 the price?
The answer is up to each individual. But I will say this: she showed up with her backup flute at our last rehearsal because her Lunn was back for repairs. Nobody noticed until she told us.