We have developed a global, ab initio-based potential energy surface for CH5 and have been doing quasiclassical trajectory calculations with it. At hyperthermal collision energies this reaction proceeds by "rebound" and "stripping" mechanisms.
As seen, the H2 product is back-scattered in this case and also is produced with little rotational excitation. This collision is at an initial relative translational energy of 1.85 eV and impact parameter of 0.3 bohr.
The stripping mechanism is illustrated by the trajectory animation you can see by clicking on E1.85_3.0_RP.mpg
In this case the H2 product is scattered in the forward direction and with considerable rotational excitation. This collision is also at an initial relative translational energy of 1.85 eV but an impact parameter of 3.0 bohr.