The wording is slightly confusing: Is the original floor unsafe, or were you unsafe during inspection?

These people probably got advice from "sound engineers" who think that the ideal space is completely dead and littered with microphones. Insist that the original floor be retained: it doesn't take much to sand, stain, and seal, and could well end up being cheaper than what is proposed.

Yes, as Jackson says, you have an acoustical treasure: protect it. I must say that I am jealous (I have gross carpet in my loft that I have been desperately trying to have removed).

...giant tapestry...

That giant tapestry above the high altar at Coventry is a profound depiction of Christ in Majesty, or (?) Christ Pantocrator. It was designed, I believe, by Chagall. The current cathedral is very (post-war) modern and is built over the remains of the mediaeval cathedral which was destroyed by German bombing in WWII.

Jackson,

It may indeed be a profound depiction of Christ in Majesty (I've been to the cathedral, years ago, but I don't remember the image), but it's still an acoustical nightmare.

Coventry does have a fine organ. I would trade with them any day. I have heard criticism of the building since it was built, one magazine even referring to it as a "ring-a-ding God box." I have always liked that space and found it beautiful in its own unique way.

If indeed you are down to an old wooden surface in your choir space, do save it and make the best of it. But it needs to be thick to have some even resonance. 20th c. flooring need not apply.
Our 1850's Episcopal Church in Gold Country, California, built by the conscripted shipwrights cum miners from Cornwall has thick, hand hewn, locally sawn, Douglas Fir, tongue and groove wooden planks under the overlay of plywood, rubberized padding, and regal looking thick carpet. What a sonic disaster. When I started Compline there 10 years ago, the carpet and padding in the loft had to go. After obtaining permission from the Vestry, I attacked the floor covering with gusto and my box cutter. All that removed, there was the original 19th century thick T&G fir flooring. It was already seasoned for over a century and had a few squeaks and loose boards. After about 400 drywall screws and my trusty drill-driver, the surface was tacked down securely. The difference in tone was striking. The singers could, at last, hear each other up there and the resonance was very even from top to bottom. Our Kleine German Tracker organ is well voiced but has no expression, and no stop less than mf, so I left the area around the organ itself with a halo of carpeting: a kind of instant EQ.
My next job is to paint the floor and sub walls in the loft with something called 'porch paint', a very hard and durable reflective surface mixture, thicker than paint with a fibreglass additive that reflects the highs more than the lows. I like the resulting sound better than with marine epoxy coatings. I built a portable floor covering for the front of the Nave with 4 foot x 8 foot x 17mm hardboard sheets (with clips) that fit like a puzzle in the space and allows the choir or whomever is performing there to hear each other and generate a modicum (that's Latin for a medium amount 8<) of reverb. They are all painted with the royal maroon porch paint to match the pews, and unfortunately the carpet. The singers were happy with the big difference in resonance.<br />jefe

The floor should be as hard as possible. No carpet or absorbing materials at all it's really simple.

As an update on our 1850's T&G fir flooring (about 22mm thick), the sound has actually gotten better over time. The difference is there is no paint or coating on the old wooden planks in the loft, and over time has gotten very shiny and more reflective from foot traffic. But, please do not move around up there bare footed.

The current cathedral is very (post-war) modern and is built over the remains of the mediaeval cathedral which was destroyed by German bombing in WWII.

@MJO The current post war 'cathedral' is built next to the ruins of the previous 'cathedral' (St Michael's 14th c.), this building was only a large parish church, the mediaeval Cathedral and priory (St Mary's 12th c.) was destroyed by Henry VIII. The ruins were found recently.

as the nation’s favourite 20th Century building.

What was its competition?

Remember: Theresa May or ….
Donald Trump or ….
Fascists or ………

http://blogs.coventry.ac.uk/uncovered/2015/05/07/the-story-of-the-lost-cathedral/

One year ago, we removed the carpet from our choir loft and refinished the wood floor. The floor is made out of maple, but there is a cutout in the center where there is pine, which shows us where a pipe organ once stood. Too bad they tore that out! Now I'm stuck with a 1988 Allen "Organ".

The church itself is a small country church that seats about 250 people. It was built in 1868. The choir loft was added in 1905.