Well i am no expert but due to the fact that the Hotspot (at least the Tri-Fi one I have) is only basically just that a Hotspot with no other components other than the radios and board as oppose to all the stuff that is in a phone, i would assume it would have stronger radios and antennas. Now don't quote me on that cause like I said I'm no expert, but I feel that might be the case.
I also see the following...
1- For every new device I've had the radios get better, the EVO 4G was better than the hero, The Photon was better than the EVO and the Tri-Fi gets signals where no other have done before.
2-its sole purpose is to grab a signal and deliver it to other devices, a phone can do that but there are so many other crap in it that it can't possible do all the dedicated work a hotspot does.
but again, this is all my opinion.
As for providing customers a tri-fi free of charge, i doubt it. I haven't heard anything of that, yet.
Getting a Hotspot from another carrier might be doable but that would mean you would have to set your Epic on wifi. I do not know if calls or texts would still come in, having a Hotspot from another carrier. I don't think so. maybe one of the experts here can tell us.
TS