jun,
the max TBF per PDCH is (about) 10 in DL and 6 in UL, that’s a 3GPP constraint.
I’m suprised that in E/// there are 2 parameters that can control the same thing.
If you are saying that the cell parameter is a market adaptation, and since you are having it available, then I’d say the cell parameter is the one commanding TBF/PDCH pilling.
So at cell level, try value 30 DL and 30 UL (and then increase gradually by steps of 05), you should see an effect rather quickly on both GPRS occupancy (positively) and GPRS throughput (negatively).
Regards,
pix