Hello,

no problem. The KMS can handle very high SPLs. Self noise is a bit higher than with studio mics, but these 6 dB difference won't matter in the case of brass & reeds.
Sound-wise, the KMS have a low end roll-off you can see in the frequency response. But, you're in the near field of the instrument anyway, so you have a bit of proximity effect > bass boost; and typically you wouldn't want too much signal content below 200 Hz anyway, with most brass & reeds.

So, just do a test recording / live thing.

Best regards,
Martin Schneider / Neumann Mic. Development