I guess a hackamore can offer more precise communication if you needed it, and also more control.
Having said that, my daughter rode her horse in a mechanical hackamore for a while, and that horse had no problem blowing through her aids.
I have ridden my Pony with just a halter and the lead rope tied to it as reins, and he responded pretty well. I don't ride him that way for lessons or really serious riding, just hacking around.
It's good that your hands are soft, because with a mechanical hackamore you do have the possibility of really being able to hurt them, especially if the shanks are longer.
To me, if riding in the halter is working, I'd stick with that. But since you've already ordered the hackamore, go ahead and try it and see how you guys do. If you get better performance, then great! Do just be super aware of your hands.
"Saddle fit -- it's a no brainer!"" - random person