tweeters- metal or soft dome?

This is a somewhat broad question. What are the particular differences between a metal, or hard dome tweeter and a soft one? If comparing the two using the same electronics and cables what differences can be expected?
With hard domes- aluminum, gold, etc what sound diferences are there. Are there various materials used for soft domes? If so what are they and what are their peculiarities?
I looked in my Guide to Home Audio by Robert Harley but could not find this addressed.
not even robert harley can provide all possible answers to the query: what is the sound of one hand clapping?
Enlightenment, don't know what it is....:-)
Jmcgrogan2- very good. Great Van Morrison reference.
You need to listen to the speakers to get an idea. There's alot of people who don't care for most metal domes but you need to hear the speakers. Just like anything there's good and bad of every example.
As a general rule, metals will be more extended, subjectively offer more "detail" and will be "harsher". Soft domes are thought to be less agressive, the best not losing out on "detail". BUT, there's a number of variables that ultimately determine how good the system sounds; cross-over point, phase matching with the mid, etc, etc.

Is this a general question or are do you have a specific project in mind?
just a general question
It depends on the specific speaker. You need to listen, not read, to appreciate the differences.
Yes all the speakers are different and you have to listen. That being said. I prefer silk dome tweeters over metal for exactly some ofthe reasons described above regarding harshness. Quality speakers give me the detail I need regardless of tweeter dome material type.
Metal domes tend to sound harder and more "metalic" due to increased ringing and a lack of internal damping. Soft domes tend to sound "softer" and more forgiving due to increased internal losses i.e. being over-damped. Obviously, any design a approach has some trade-off's and benefits.

This is why some metal domes are "treated" with a damping compound i.e. to reduce the ringing. It is also why some soft domes are "doped" with chemical treatments i.e. to increase the rigidity of the driver itself, which reduces internal losses. Both approaches strive to achieve the same effect i.e. improved transient characteristics with a more linear power transfer over a wider frequency range with lowered distortion. There are any mass combinations that one can achieve and / or strive for, so most of that is up to the designer of the driver.

How any individual tweeter sounds is up to the speaker design itself. This is due to such variables as crossover point, crossover slope, placement on the baffle, size of the baffle, baffle shape, baffle contour, the quality of internal crossover & wiring parts used, etc.... This is where "art meets science" and what determines the over-all sonic presentation that we hear and measure. As such, there isn't anything set in stone in this matter, hence the above comments about being a very broad subject to try and assess in a forum thread like this. Sean
Thank you for weighing in on this. I had hoped you would. I am going to upgrade my speakers in the future, although not too soon. In the meantime I am trying to educate myself to the basics of the technology before I do some travelling to listen to various models, as I do not live close to high end dealers.
Danlib1, good catch.
Are you another Van the Man fan?
Did Ye Get Healed?

Yes Dan the man is a Van the man fan.

But after Enlightenment I kinda lost my feel for the newer stuff, tending to slip back into the mystic.
These days alot of makers are using ribbon tweeters these days. You should hear some speakers with ribbon tweeters also. You may find dome tweeters don't cut it for you.