I would like to have, mobo with following features :
A1200 and A4000 CPU slot, so that any A1200 / A4000 accelerator would be useable.
At least 4 Zorro II / III slot, so that Zorro mode would be selectable, no matter wich accelerator is used. I mean Zorro III mode should be availlable even if A1200 accelerator is used. Should be doable, RMB did it as a prototype.
At least 2 active PCI slots. But Zorro slots are more important.
I love the 1200 and own several but...you are asking for stuff that has been done. Building on the 1200 makes no sense at all. its not a proper full 32bit design to start with..bad power supply,motherboard bugs,slow unbuffered ide,EC cpu, its like buiding a house on a mud foundation or in pc terms.. trying to build a 386 into a gaming/full blown internet machine.
zorro2 and 3 use the same slot, theres no need to make it selectable, either card works in it in either mode automagically.
The 4000 is more bang for the buck from the get go. Having said that what i would like to see is a new 4000 board with onboard 060,512k fast ram,pci or pcie slots native,with usb,ethernet etc local bus to the cpu,eliminating bottlenecks. I cant undertsand why anyone would build on a 1200 when they want what the 4k has. its not cheaper and all the added 1200 dongles generally make it where something is bound to not make good contact and start acting up. Even if you take a 1200 all the way,the bppc is still way slower than the csppc-not to mention csppc uwscsi rocks,and you still dont have proper zorro3 because 1200 is missing buster chip(i said proper,not the buggy z3 busboards or the hokey ziv overclocked zorro2). It may sound like i'm down on 1200's but im not, i'm just stating hardware facts.