My Quest for a 7 inch Android "Phablet" that will Function on T-Mobile

I am deciding on whether  to leave the Verizon network or go to T-Mobile.  I have hesitated mainly because I currently have a grandfathered unlimited data plan and am reluctant to lose it.   In addition to my Verizon plan, I recently picked up a $70 unlimited T-Mobile plan and am using a Huawei Ascent Mate 2 (6.1 inch phone).  I am now trying to decide on which network to keep.  The goal though is to find a 7 inch device so I can stop carrying both a tablet and a cell phone around, and most importantly, to gain the extra screen "real estate" since I use the phone so much for data/browsing/reading. 

Unfortunately, in all the research I have done, it appears that T-Mobile uses a frequency that is not supported around the world (LTE), so my original thought of using any international unlocked GSM phone does not seem to be feasible, and, maybe switching away from Verizon is not as important as I initially thought.

Here are the phones that I’m interested in, with the network frequency they support:

Huawei MediaPad X1 / Huawei Honor X1 (7 inch)

2G: GSM:850/900/1800/1900MHz
3G: WCDMA 850/900/1900/2100MHz  TD-SCDMA A + F
4G: TDD-LTE:B38/39/40/41, FDD-LTE: B1/3/7
Data Services GPRS / EDGE / WCDMA HSPA + (DL: 42Mbps, UL: 5.76Mbps) / TD-SCDMA/TD-HSPA (DL: 2.8Mbps, UL: 2.2Mbps) / TDD LTE (DL: 112Mpbs, UL: 10Mbps)

HP Slate 7 VoiceTab Ultra (7 inch: possibly rebranded Huawei MediaPad X1)

GSM at 850/1800/1900 MHz
WCDMA at6 900/2100 MHz primary with a printed circuit board (PCB) design to support 850/2100 MHz

OrientPhone Mega Pro 7.0 (7 inch)

2G: GSM 850/900/1800/1900MHz

3G: WCDMA 850/2100MHz

GSM+WCDMA

Samsung Galaxy Tab Pro 8.4 (8.4 inch International)

I actually purchased and tried this device but service was not reliable.  Sometimes I would get HSDPA+ other times slow as a dog. Also, it was just a tad too big for everyday practical use.  7 inch seems to be the sweet spot for me...

HiSense MaxE X1

Not enough specs out yet.

Sony Xperia Z Ultra (6.4 inches)

This is the option which I am about to pull the trigger on because I know for a fact it will work on T-Mobile LTE.  Only hesitation is that I really would like that extra half-inch and an LED Flash for the camera.

Huawei Ascend Mate 2 (6.1 inch)

I am currently using this now on T-Mobile LTE (1700/2100 Mhz).  It is actually an awesome phone and have no regrets purchasing it.  Battery life is unbelievable.   Can literally go for days with normal use.  But, as mentioned, I would like a bit more screen real estate if possible.

So, IN SUMMARY,

I know that only a couple of the above phones will function with LTE on T-Mobile.  But, I am not sure what results I will have with the other phones.  I definitely don't want normal 3G speed, but I could possibly live with HDSPA+.  With the little experience I have with the frequencies, I am thinking that the only frequency that I can take advantage of with most of the above phones is the 1900 Mhz frequency that T-Mobile has re-farmed (I am in a re-farmed area).  Only problem, T-Mobile doesn't guarantee that frequency will work or if the service will be reliable enough.  I believe I found this out while testing the international version of the Galaxy Tab Pro 8.4.

Anybody have any feedback on the above, or have any other experience with 7 inch phablets on the T-Mobile network (obviously with calling capability)?  If so, please share the phone model.

Thanks.