It's been my experience that the cut of the headjoint is more influential than its material, though subtle differences arise with different materials as well. Often, a solid silver body only enhances resale value

, but different weights can influence tone and response a little--I definately prefer the heavy-walled Yamaha to the regular. One of my students last year bought a Muramatsu EX, which has a silver head, but a plated body. It sounds amazing!!! (Cost around $2600.)
The B foot is nearly standard in the U.S., but not in Europe. More contemporary literature is being written using the low B, and I think it's easier to just get a flute with the B than scamble to borrow one should the need arise. Four of my students recently played Gary Schocker's
Nymphs quartet, and the fourth part is
riddled with low Bs. It does change the instrument's response, but I wouldn't give it so much credit for enhancing dynamics (that's the player's job

). Just play a bunch of flutes with different features 'til you find the one that works best for you.
As for playing louder, do you play with much of the embouchure hole covered? This will create a clear, but very thin (and usually out-of-tune) tone which doesn't project very well. It's difficult to adjust to playing in a more-uncovered position, and your upper lip will have to work a little harder to figure it out, but the tone and intonation advantages will be significant. Check Jen Cluff's website for lots of articles about tone and technique.
