The UA9 experiment has been operated for some years in the CERN-SPS in view of investigating the features of the halo collimation assisted by bent crystals in a two stages collimation system. Silicon crystals a few mm long have been selected for an optimal channeling efficiency. The crystal orientation was easily optimized and the collimation process steadily achieved with the installed goniometer having an angular reproducibility of about ± 10 µrad. The loss profile in the area of the crystal-collimator setup was strongly reduced by about an order of magnitude, whilst the off-momentum particle population resulting from the interaction of the primary halo with the bent crystal was reduced by a similar amount. The measured loss was consistent with simulations and with single pass data collected in the North Area of the SPS. In recent runs at high-intensity and high diffusion halo speed, a reduced loss regime was observed also far downstream of the crystal location. The accumulated observations strongly support extending the UA9 tests to the CERN-LHC collimation system.