I'm considering a switch to the 2013 Blade 18x20 from the P1 16x19.
Hitting with the P1 is sublime - great power, plow through and feel is second to none. As much as I didn't find the weigh too much at first, I had a losing percentage in league play form Sept-Dec and found myself lacking energy at the end of matches. I also find the power a little hard to control. If my footwork gets sloppy (late) or contact point is off a little, the ball sails.
During the 1st outings with the Blade, the lower static weight and increased control of 18x20 are obvious. Mishits result in more shock transfer and some elbow discomfort after matches. I'm hitting heavier balls with the Blade, which surprised me; this is probably due to higher racquet head speed.
It's fairly easy to switch from one to the other as the SWs are similar. I've had 2 great wins with the Blade so far and bought a 2nd. I'm hoping that, as I get more used to it, the discomfort will subside, as my hitting will adjust to the Blade.
Steams 99s, leather grips; 4G @58lbs; ZX 16 / marathon 15L @62lbs