I am on TMo too and I have to say my signal strength seems about the same. In regards to Tmo and signal strength there are actually multiple variable at work.
1. New phone whose user experience in regards to reception capabilities seem to vary. With a larger phone you could theorize that signal strength should be better because you have more "space" for antennas. Also the V10 has band 12 which could have an impact.
2. Speaking of band 12, another variable. If band 12 has been "lit up" in you area, that would have a major impact on your perception of signal strength, especially indoors. Also, especially if you are coming from a device that does not have band 12 support and band 12 has been "lit up" in your area. For me, no band 12 love in my region yet.
3. TMo has really been building out their network, converting older towers to LTE. Again, depending on where you live, the density of TMo towers may have increased leading to the perception of better signal strength.
I think when we get new phones, we pay more attention to things like signal strength so I'm not surprised by the discussion. For TMo subscribers though, I think we have to be careful in terms of giving too much credit to the phone. There are just too many things in motion within TMo's network.