Would I use them for recording a concert, hell no.....
Actually, they are very good at concert recording - it depends on the concert, the acoustics, the conditions and the boundary mics you have.
Mine are the best - but *not* cheap.
I have a pair of the Neumann
GFM 132 The others suitable for quality recording are the top of the Crown PZM range.
But the cheaper boundary mics tend to be designed for PA work and I wouldn't use them for recording - the exception being the Tandy PZMs - a little noisy (but very cheap), but acceptable once modified to balanced output and 48V phantom.