I dont think PCI was a good choice on the A1200, I had the LT4 version and sure you could run a 1600x1200 WB, but running fast scrolling graphics on the Workbench was slower than regular AGA in 4 colors. For example, scrolling in Ibrowse felt laggy and this was with a 060 board. If you wonder what I am talking about, play a module in Hippoplayer and enable any hipposcope. Watch hipposcope run in slo-mo.
As I was told this is because of how memory is shuffled to the GFX-board on the A1200. I was told that on on a Z3 system this issue is gone.
Another nice detail about a loaded PCI system is that the Amiga will use around 100w if it is pumped to the max (PPC/060/Mediator loaded system).