I'd suggest you might want to do a little research first. Using Boeing's figures the 744F has a max structural payload of 112.6 Tons, while the BCF is 113.5 Tons. The 744F has a MTOW of 875,000 LBS while the BCF has a MTOW of 870,000LBS.
I suggest you do your research a bit deeper, then, and compare apples with other apples... From
http://www.boeing.com/commercial/747...400f_prod.html :
Maximum Payload:
248,300 lbs (112,630 kg)
Optional 273,300 lbs (123,970 kg) available with maximum takeoff-weight limitation
That 123.9 tonnes is a LOT closer to the structural payload of the 744F with the higher gross weight. In fact it is over 125T in the aircraft I have flown.
So, the SF gives up AT LEAST 10 tonnes of payload (8%), plus the volume (16 cu. M) and range (7.8%) hits and reduced flexibility with the lack of nose door.