They are benchmarks on real hardware, and I tried to provide enough details so that anyone can reproduce them (but some of the benchmarks are on servers I have that you can't order on public cloud -- these ones are clearly marked). "Synthetic" means that the data is synthetic, not an actual production workload. For instance, some of the benchmarks use files filled with random bytes.
Do non-randomly ordered bytes produce different results??
Syq has compression turned on by default. Also, if you are updating a file that already exists on the other end, syq will only send blocks of the file that changed.