I had two 4 slot motherboards in my AltairKit 8800 and it was getting kind of tight trying to fit in a CPU, memory cards, serial card, rom, and disk controller, so I upgraded to one of Grant's 18 slot motherboards. It's beautifully built, just like the rest of his cards, and works great.
Out with the old, in with the new. The old motherboards look kind of puny next to the new beast.
Plenty of room to expand, if the power supplies can keep up.