The scenario: fly from T00 to 3R9. I set it up, 1,000 ft to 10,000 ft, fuel stops (but I don't need one), and to avoid B,C,D but not stadiums (because there's one in the way, when I set a course manually as shortest distance, under the Class C outside ring).
First attempt (it gave me an unneeded fuel stop, but I'm more interested in how it deals with the Class C and Class D):
It routes me around both the Class C and the Class D.
I tried it again, removing fuel stops (I don't need one):
This time it routed me over Class D, but outside the Class C.
So you can see why I am asking for routing under the wedding cake... it doesn't appear to work for me (for this one scenario). Here's what it looks like when I route it manually:
I avoid the Class D and fly under the Class C outside-ring.
I do wonder what kind of rules it follows about space-above and space-below. In this scenario, the outside ring starts at 2100 feet and ends at 4500 feet. I could easily fly at 1600 feet and avoid any/all antennas under the ring, and be more than 1000 feet AGL for most of it. Granted, there are a few spots where my AGL will be below 1000 feet, but I could fly a bit higher still and keep it under 2100 feet, maintaining the 1000 ft AGL. If it looks at "highest point" along the route under the ring, then, yeah, there are antennas up to 1049 feet MSL, so it may avoid that route for that reason. (But it still shouldn't venture into Class D!)
I ran it with 4500 feet as my maximum, and it routed me around the perimeter of the ring (to the south)... i.e., not under the outside ring. I would think that, if routing me around to the south, it would have put me under the ring... but it didn't. It may be that it takes the quadrant maximum (in this case, 2,200 feet) and uses that as the minimum (+ 100' ?) for all routes. I dunno.
Yes, this is just one scenario and if I run it on 20 others, then 19 of them will be pretty good. But it never hurts to ask!
The fact that they've attempted something like RealPlan is impressive... even the most simple scenario likely involves hundreds or even thousands of variables, rules, assumptions, etc. So, my hat is off to them for trying, and I certainly won't get too upset if the RealPlan route needs to be tweaked.