Our service was installed 7 weeks ago, and it has been rock solid. At this point I have transitioned out of the new fiber user mode of repeatedly running speed test. It has consistently given excellent results. In terms of real world performance, a couple of nights ago Steam delivered 8 gigabytes of a game download at 98+ megabytes per second sustained. My wife, without prompting, noticed that her large cloud uploads are taking much less time. Equally important to me but harder to characterize (not enough data yet, or the need to fully instrument this) is that latencies appear to be relatively low. Working remotely (generally ssh or mosh terminal sessions) I have not yet noticed any issues with packet latency through Sonic.
Thank you Sonic. The fiber service is an excellent product at an excellent price.