The manual states that in 4 0hm it has 340wpc but bridged mono, the figure stays at 650w whether 8 ohm or 4 ohm. I don't know why. All I can say is, it's a very strong amp.
I checked a catalog for PA equipment and found the Mackie and Crown amps that you are talking about. I don't pay much attention to PA amps and they probably don't belong in home stereo systems. The reasons that so many used the DC300A for PA and professional use is that it was strong enough to do it and they have been available fairly cheap used for many years. The amp also uses 1/4 inch connections which lends itself to PA and you need adapting patch cords from normal RCA to 1/4 inch which were supplied with them when new. These new amps are designed for PA use, they will have much higher distortion than the old DC300A. Honestly, I would not buy any of them for home stereo. The old amps on ebay are still going for $250 or less and in spite of their age, are a good buy. I wouldn't be surprised if these are still going strong when the new ones have crapped out.
Bill