Large scale spectroscopic surveys EUCLID:  VIS (<24.5 AB) + YJH (<24 AB) wide imaging survey over 15000 sq deg  YJH < 26.5 (AB) over 40 sq degs,  slitless spectroscopy (J ~ 19 ) VLT-MOONS (proposed):  500 sq arcminute, 500 object NIR MOS  deep survey key element of science case  scale height for LT dwarfs  c.f SDSS for M dwarfs!