I feel like my reception is similar which is disappointing because T-Mobile never deployed band 12 in my area, but had deployed band 71, and now that the XS supports it, I'm not noticing any better speed or signal penetration in my basement. However I did manage to pull down 490Mbps WiFi on SpeedTest.net app when in my office while only 5-6ft from my router which seemed like a big improvement. So at least the WiFi seems better.
Ok, so I just looked into band 71, and I guess T-Mobile lied to me on the phone when I talked to them about it last year. They said that band 71 would be deployed in my area last autumn so I was disappointed the iPhone X didn't support it. When checking a map from this spring that I just found when googling, it shows that it's not in my area yet, and I found another map that said it will be in my area by the end of 2018, so it's entirely likely that I don't even have band 71 yet. Lame! I've got band 12 a couple counties west and band 71 a couple counties east and nothing here in the middle in this decent sized college town.