the Pro Staff Classic??? let's see... i used to play the white butt cap version, both "si" and non "si", no difference really... the PSC i feel cuts at and through the ball better. backhanders at the net are best with the PSC. PSC produces better flat type shots. the PSC's feel is stiffer but response is faster... it's a tight racquet
the n6.1 95 is a solid racquet... feels less stiff. produces power easier. the control is still up there butstill less than the PSC. the n6.1 i feel is more forgiving... off center shots aren't as bad... serving with the n is still very nice, but for sniper like accuracy i would have to give the nod to the PSC, but the n possesses some good pop.... the n produces more spin from either side, top-spin that is... the PSC slices and punches better.
if you can get your hands on a white butt cap PSC in good condition, get it! try them side by side... both are tops in my book... i started playing with the PSC well over 10 years ago and judge all other racquets by the PSC.