What is the shape of the vault (ceiling) and general proportions and materials of the other main surfaces (floor/walls) of the space?

Thanks for the detail; it can matter. In that case, I would imagine a wooden vault would add resonance. But it may also depend on what, if anything, is immediately above the wooden layer.

For accurate predictions, you need an acoustics consultant who understands live sound and has a proven record of working with churches.

They will measure various aspects of the space and use modelling tools to understand how God's laws of physics apply in your situation.

Anyone else is guessing.

Tangent: for folks who've never seen a glorious wooden roof, here's the famous double-hammerbeam angel roof (constructed in the generation before the ravages of the Reformation) at St Wendreda's in March, Cambridgeshire:

https://c1.staticflickr.com/2/1666/25876154796_9c3c9b754f_b.jpg

There are a number of angel roofs in England (especially East Anglia), but that is one of the most famous. Yes, the Continent has many glorious stone vaults, but these wooden roofs of parish churches in England are among the special glories of that island.

Here's a visual, with music (to get back to music...):

https://vimeo.com/73653553

I know lots of American Catholic sacred musicians may dream of French Gothic expanses (I prefer my Gothic in smaller jewel boxes (the various chapelles of northern France) or the Backsteingotik of northern Europe), but in my dreams I would likely choose a not-huge Romanesque church with fine clerestory lighting and a wooden roof like these....

Eamon Duffy might well agree.

I just started working for an acoustical surfacing company (andersonsi.com), and they have two wood divisions, Architectural Surfaces and AcoustiGreen. I would be chuffed to bits if your architect spect our company, but the sites may give an idea and info on what is possible acoustically.

Incidentally, my job there is going to involve learning acoustics so that I can assist in modeling rooms to determine best acoustical solutions. Any ideas for studying acoustics at a deep level, including school?

The surface of the wood material makes a big difference. A hard surface will reflect the high frequencies. I used a dark red fibre glass laden porch paint on some of our loft surfaces to good effect, especially when combined with dumping the carpeting. It pumped the highs, and was very tough as you would expect a porch paint to be. If you have an older parish, which, i will surmise is almost everyone on this forum, what is the first frequency range that goes especially in older men? The thickness of the wood makes a big difference too. Our loft has 1874, 1-1/2 inch thick, tongue and groove planks, 6 inch wide, very old and hard Douglas Fir floors which both resonate and reflect most frequencies well. Our old stair well to get access to the loft acted as a black hole for long frequencies so I cut a piece of plywood (as thick as I could lift into place) with the same porch paint applied, to close the black hole for Compline thus improving the low freq. projection. It's probably illegal but the local constabulary has bigger fish to fry.
After 38 years of playing the concert halls of the world with the LA Phil, I have a lot of memories of great acoustic spaces. Why is this even in the mix? Only that there are a lot of dependent issues. The Musick Verein in Vienna sounds great but it has nothing in common with Symphony Hall Boston, also a great hall, with almost every construction aspect different. Nothing compares to playing the Bruckner 4th in Ghent, which was a late medieval, all stone cathedral. The only reason it worked at all with the 6 second echo (at FF), was because the harmonic rhythm was so slow. Yes, I took an Acoustics of Music class at University, really my favorite class while there, and discovered that the more i learned about acoustics, the less I knew. A few thumbs are these: try to keep the surfaces made of the same material, else they cancel each others' resonance out. Thicker and harder is better than thinner and softer. No parallel surfaces, unless you enjoy flutter echo. Ditch the rugs. Almost anything is better than soft plaster. If you must plaster, consider HydroCal, a very hard alabaster plaster that reflects well and stands up the Anglican Abuse. 8<)<br />jefe

you main gain some knowledge by comments here but you will not get your answer here. you must do modeling to get a true projection that takes into account shape, reflectiveness of materials, placement of instruments and musicians, etc. I don't think it's as simple as replacing one material with another. JMHO