Has anyone had any experience making multiple SimConnect connections to a P3D session? How well does P3D handle pushing data from two or more SimConnect connections?

When you consume all the bandwidth on a single simconnect connection it will have a negative effect on performance with in the sim, this can range from minor or bad stutters to a 50% or more drop in fps.

If you plan to use simconnect to inject 3d objects in to the sim that can go really smooth but the more objects the sim has to draw that way the higher the chance of seeing some stutters while loading the 3d objects.