Photographers really can cause distractions at classical concerts particularly if they are using modern SLRs. The noises somehow gets "amplified" plus a dose of reverberation!
Sumi-Jo was in Singapore, and a photog with his Canon (read: 70-200 white cannon) snapped off something like 10++ frames within the first minute, then stopped until it was time to present flowers, meet the dignitaries on stage etc. Heard his camera clearly when he was taking the singing shots off-stage, along the middle aisle.
I also shot Sweeter Than Roses' actual performance that Sunday, but felt restrained as I try to minimise the distractions while photographing.
Maybe an idea is to use a rangefinder, or a pin-hole camera (duh!) ;p
Scriabinesque, what do you use to do live recordings? Where do you place the mics?