Is there any reason that WorkerThread is a boolean instead of an unsigned integer? I would love to be able to control this a little more. Perhaps test if it is set, see if number and if so then use it as-is else use it as a boolean else fall back to defaults?
// In Source/Urho3D/Engine/Engine.cpp:190
unsigned numThreads = GetParameter(parameters, "WorkerThreads", true).GetBool() ? GetNumPhysicalCPUs() - 1 : 0;