Exact quantum reaction probabilities for a collinear model of the F + HH, HD, D D and DH reactions on the MV potential energy surface have been computed using hyperspherical coordinates. The results, obtained up to a total energy of 1.8 eV, show three main features: (i) resonances, whose positions and widths are analysed simply in the hyperspherical formalism; (ii) a slowly varying background increasing for FHD, decreasing for FDH, and oscillating for FHH and FDD, whose variations are interpreted by classical dynamics; (iii) partial reaction probabilities revealing decreasing vibrational adiabaticity in the order FHH-FDD-FHD-FDH.