I've been using it with a holosight in TDM to see how effective it is, and I'm liking it.
I's the same as every other semi-auto rifle (apart from the SKS) except it has a 20 round mag instead of 10, so there's no reason to use any other semi-auto over the M417, it works well enough in CQB to give you an all-round weapon option, which is necessary to play the class usefully, as you can act as squad DM and still have firepower when in close to the objective, without losing your long-range ability by taking a PDW or shotgun.