look
you don't upgrade from a high end designated card (at the time) to a lower designated card in comparison to the modern lineup.
do you see the 5 in 250? it means that this model is midrange. the 9800, with the 8, was designated high end. If you upgrade, you upgrade from high end to high end, or mid range to mid range, or midrange to high end. You *don't* go from high end to midrange.
For a more (exagerrate) example of how this works, consider the nvidia 7 and 8 series. A higher end designated 7950 and a mid range 8600. See the 9 in 7950 and 6 in 8600? We all know that the 7950 gpus are faster than the 8600, so anyone who "upgraded" from a 7950 GT to 8600 GT was really lazy to read reviews.
9800 to 250- that's going from high end to mid range. This card is just to occupy the gap between the 240 and 260 cards. If the performance is there from an older gpu, then why waste more money on research and development for a downgraded GT200 that won't have a increase in performance?
If you upgrade from the 9800 GTX+ to GTS 250 because
#1 You were uneducated about nvidia's naming scheme
#2 You didn't bother to read any reviews
then the fault is with customer stupidity.
second note:
BFG tends to release only factory overclocked video cards (at the same price as other companie's reference cards) , its hard for me to find nowadays as stock reference card from BFG