This is really awesome, definitely keep the SMG as it is, it's very tactile and enjoyable to reload. I especially like how it's possible to reload on the move also.
EDIT: want to add, I really appreciate the decision to not have dual wielding! So far the two weapons have a lot of differentiation in where I choose to use them. Whatever the third weapon is, I hope keeps up this trend and has it's own set of "best use-cases" that the sidearm and SMG currently don't fulfill.
Also, for once, the sidearm really makes sense to switch to when I have to reload the SMG, whereas in a lot of other games, that advice is usually just a random loading screen hint.