Yep, I noticed the same; when I've been watching I see that most seem to be doing 90 kts at 1800'... even most Bonanzas and Mooneys! I did see a King Air flying the high route; I kinda wonder why he didn't do the turbine/warbird arrival? Odd.
The North 40 is pretty full, but HBC and HBP have plenty of space. Maybe the forecast of good weather has spread out the arrivals, as opposed to clustering them around weather events.