how many musicians per jam

[Dimitri Muskens]

Assuming good gear and decent internet bandwidth ( 35 down, 5 up or better), would you expect expanding a jam from 4  to 5 members to tip us over the edge in terms of latency?

We're all within 70 miles of each other in the greater Seattle area.

>>>
Nope, shouldn't be an issue.
Although 5up is rather meager. (remember it's Mbit., not Mbyte)