Not sure of the exact numbers,but the 747-8 would be almost identical to the 747-4, since only the external views are modified.
The MD-11 definitely has better FPS than the 747's, since it has much newer code.this, in spite of having more complex FMS and flight dynamics.
The MD-11 is its own beast, kind of a cross between a Boeing and an airbus. Its probably my most favourite modern heavy!!!.
I was considering upgrading to the 737-NGX when it gets released. Someone had hinted that it would be similar in performance to the MD-11 and since I don't own it, I thought I'd ask.
Core i7 2600K @ 4.5 GHz (HT enabled), Asus P8P67 Deluxe (B3 revision), 16 GB DDR3 1333 MHz RAM, Asus GTX 670 4 GB OC, Crucial M4 SSD (OS & FSX drive).