Hi konaboy,
You are going to have to play behind a drum shield with a lid eh? That's a tough one especially considering they have told you that you already play the room appropriately. It is commendable however that your organization is taking it seriously and is hiring professionals to figure out the sound.
If we accept the argument that a drum shield helps to reduce stage volume and mic bleed and it increases instrument isoloation/seperation it seems pretty obvious to me that all of those benefits would be somewhat negated by the fact that one of the musicians will be playing on stage inside a structure with a roof on it. It's one thing to have a drum shield.....but to put a roof on it is starting to push the boundaries of what looks appropriate on stage for a live musical performance.
If the room is that bad acoustically speaking then maybe something should be done about the room before they consider having musicians play inside plexiglass structures. Maybe try suggesting the following.
1. Acoustic panels strategically placed in the room might be an idea.
2. Even playing an electric kit to trigger some really good acoustic samples off of a laptop wouldn't be terrible.
My point is that there are other ways to solve this issue.
If the musicians need to be this isolated on stage then they could consider doing the show remotely from a separate acoustically treated room and have a video screen in the room with the audience.
That being said if you end up playing inside a shield then you really should have your own monitor behind the shield with you so you can hear the other musicians and you need to make sure you have a good mix in it as well. That is the deal. No monitor/No cage
Of course using appropriate hearing protection is a must in any musical situation as well.
Isolation is great and I empathize with sound techs. They have to work with a lot of musicians on a regular basis that despite being good players may not be knowledgable on how to maintain and set up their own gear properly (on a technological level) which can result in really poor sound. A good example of this is when a player turns their instrument up on stage in order to hear themselves after the level has already been set at the board by the sound tech (there amp is mic'd). This not only makes their instrument louder on stage but louder out front in the mains as well. What they really should do is ask the sound tech to turn their instrument up in the monitors (which are on stage facing the musicias and don't really affect the mains). It's also very common for bands to play so loud on stage that they are over powering the mains with their stage volume. The sound tech generally puts the mains at a specific volume level because that is the appropriate volume level based on the type of event, type of audience and acoustics of the room. So the sound tech can't realistically put the mains any louder then that. If the bands stage volume is louder then the mains then the audience will hear a lot more of the raw stage sound. This means that the audience is hearing some of the raw unE.Q.'d and un mixed sound from the stage without any effects. Also, different instruments and amps may have different directionality to their sound. So although the mix may seem okay to the musicians on stage it may sound very unbalanced to the audience.
So I understand that sound techs go through a lot and need to come up with solutions to re occuring problems.....but a shield with a roof on it is a bit much of you ask me