For the 4th time, I'll happily run a high level (lets go 17th this time) one shot, cleaving closely to the DMG encounter creation/ adventuring day guidelines, and ill run it for 5 of you.
I bet you London to a Brick the Wizard is not OP compared to the other PCs.
One of the issues is that lots of people hate running/playing under the assumptions the rules describe. The eight encounter day a big example. Is it the fault of the Rule writers for making something too stiff or players for ignoring the rules?
Edit: I got ninjaed by the above post!