So, I got both XB1's on an open NAT, and things work, for the most part, without having to reboot pFsense.
First, I tried adding an additional router (Linksys EA6400 AC1900). Basically it went Modem -> Linksys -> pfSense -> internal network.
The linksys had wifi enabled and a hardline to the XB1's. Only enabled uPnP, no port forwarding. During that, I found that XB1 boot order mattered. /boggle
Anyway, so i wondered, if this works, what i move everything back behind pfSense and get rid of that extra hop. So I did.
Lo and behold, using the "proper" boot order does matter, at least for me.
A little more about that magical boot order:
I have both XB1s set to energy saver in power options, so they completely shutdown.
One XB1 (XBA) was bought within 3 months of XB!'s release.
The other (XBB) was bought about a year after release. Don't ask why this matters, even microsoft is "dunno"
So, If I boot XBA (the older one) first, THEN boot XBB (the newer) both get an open NAT, and everything works great.
If i boot them in the opposite order,XBA gets strict and XBB gets open.
I have no idea why this matters aside from the older XB1 will get the default ports and the other relies solely on uPnP.
Side note from Microsoft, aka hill-billy tech support:
When I first talked with them about what ports should be forwarded, they could only say "follow this guide and make sure ports yada yada were open".
Given that (Like Bradenmcg says) ports 53, 88, etc are garbage ports, everyone allows those outbound. I asked microsoft, "OK, make sure the ports are open… So, which direction and which protocols?"
I asked that 3 times, kept ignoring the question, finally they said, (after dropping packet capture results, basic networking rules, etc on the poor guy) he said "I'm sorry, but what you're talking about is beyond my ability."
It just so happened that during the chat session I found the "proper" boot order for my XB1s. Told chat about it, asking if there was a known problem with what I was calling Gen1 XB1s, because obviously, there is a problem. They said there is only 1 generation of XB1. They said the last resort was to reset it to factory defaults (Sorry, I don't feel like downloading 120GB of data tonight and re-setting everything back up, fix your networking) and see if that fixed the problem.
Finally after getting both working with open NAT on that boot order thing, they asked if there was anything else they could help me with... lets say i really wanted the ability to post a Jackie Chan meme in the chat box.