I dont even care about ts infinity at this point because its an abomination to the name halo.
But as far as TS Pro goes, sprint allows people to flank way to easily. I find myself being killed from behind/all directions far more in h4 than any other other. This is also because of instant spawn and people just hold sprint to get back to the spot where they were killed.
Not only that but H4 is a melee fest. Sprint at someone and melee. That pretty much sums up H4 gameplay.