I posted this thread a couple of weeks ago -
http://www.dslreports.com/forum/r29104039-The-truth-about-FiOS
In that thread I suggested that over-subscribing the service to my neighborhood was the actual source of my poor upload speed and reliability problems. My main purpose was to dispel the myth that FiOS isn't split between customers in a similar way to other cable technologies. Yes, it is technically somewhat different, but it doesn't prevent over-subscribing, it doesn't prevent your service from being effected by other people using more bandwidth than Verizon allowed for. 
In response a couple of people (Thanks buckwheat1980 and McBane!) suggested getting Verizon to switch my connection so that it is routed through a GPON instead of a BPON. That did indeed fix my poor quality upload connectivity.
So, if you are having trouble streaming to Twitch or some other service (I tried several myself) and/or have other excessively long or problematic upload issues, this might be the solution to you problems.
What it required was for me to request 150/65 tier internet service, which requires a new ONT and different routing through Verizon's servers than services at or below the 75/35 tier. There will likely be some kind of charge to switch to the higher service. After the technician came out and installed a new ONT at the house, and then changed my connection at a different location near my house, my streaming was rock-solid.
I couldn't afford to pay the 150/65 subscription fee, so I switched back to 75/35 a couple of days later. Because the hardware and routing was kept the same with the downgrade (they don't come out and switch you back to your old ONT), I retained the excellent upload service. Problem solved. 
Too bad it took 4 months and looking outside Verizon for a solution.
                       
                           
                       
                     ↧