The P series are what I would call "okay" amplifiers. They put out good power, although less than you may think... the big published number is a dynamic rating. For instance the P1500.1 is rated for 1250 watts RMS in the manual. Some folks cite bench tests at 1800 watts... that is at 30% THD, so I don't consider that a good number at all. They do fine at their rated impedance, and no lower. They also do their rated power at their rated THD, and no more (until you get way above rated THD).
Short answer... good for the money.