Verizon iPhone 7, 128GB Gold. Loaded IOS 10.1 Public Beta 2 with Verizon 26.0 last night. So far, so good using Data Roaming; Enable LTE; Data and Voice. However, no long trips, so far. Did go into my WiFi settings on my phone and changed DNS setting for my phone to 8.8.8.8 (Google). Interestingly, when I switched off WiFi, SpeedTest by Ookla indicated no cellular service whereas 4GMark tested and provided data for cellular. Previously, on IOS 9.3.5 SpeedTest worked fine when WiFi was switched off.
Secondly, on IOS 10.0.2, previously I found that enabling LTE to Data only seemed to fix the issue, but that may have been because I live close to I-95 in Northern Virginia and LTE rarely drops below two dots.