Hello and welcome to this forum.
Regarding HD Voice, there is no mention, so I have my doubts.
Please understand, that I have taken the freedom to remove the link at the end of your posting, as it was not connected to your posting and therefore might be considered spam.
Everyone interested can still look it up.
EDIT: I was a bit slow and therefore removed all the double posting.
Overall it looks, like the FP 3+ is somewhat lacking for your needs.
And you should always keep in mind, that every repair issue in the US needs to be serviced here in Europe. So you have to buy and ship spareparts or the phone. And coming by a spare battery might not be that easy either, since they are considered hazardous goods when not shiped inside a device but on their own.