I have had some success connecting to my Bluetooth devices but only when I'm in the same room as the Rpi. This limits the utility somewhat... I had hoped to be able to use them anywhere in my home. I will (eventually) move the Rpi into a more central location, but I don't think that it will give me sufficient range.
I would like what seems to be 15-25 meters (max) through drywall/lumber walls on a single floor.
It's my understanding that the Rpi 3 does have an unpopulated antenna connector, but that this is only for the wifi (I use ethernet).
Are there any USB adapters that might solve this problem? The only ones I can find on Amazon are those low profile ones that stick out a quarter of an inch. I can't imagine those will be a superior option (probably just for keyboards/mice a few inches away?).