I checked the speed on a few shots, and filling the base adds about 50fps from my T/C Greyhawk using 80gr of Goex 3F. I used Crisco.
Because the evaluation was for an elk hunt, I also checked the difference with a .50cal over powder card/.510. The card had no effect when used with a Crisco filled base. The main reason I used the card, was the gun was to remain loaded for several days, and I didn't want a poof when I pulled the trigger.
Not sure it worked better, but I felt better.