Correct on the 4 ohm power, they are speced as though they double power
@ 2 ohm but in reality the 4 ohm power is just higher than speced and
the amp shows a typical increase of 50-60% from 4 ohm to 2 ohm.

How much higher is "just higher"?

I'm not sure how many versions of the original P450/650/850 there are,
but your assessment of them sounds pretty accurate. The ".2" version has
two versions, the first-gen was being produced in Phoenix and we then
debugged it before moving to turnkey production at the same factory that
had produced the PCB's all along. The ".2" models are pretty much
bulletproof and work flawlessly, provided you're willing to spend a
couple of hours getting acquainted with the front end features so the
installed product is configured optimally. It's easy to get in a hurry
and screw up the signal routing or make conflicting crossover settings.
I guess that's the penalty for having as much control and versatility as
these do - it does require a more competent installer to get the best
out of the installed product. Which isn't all bad...

Yeah, I finally found a somewhat competent installer to install my gear, but
they royally f'd up the crossover settings on both of my a/d/s/ amps
(P840,P240) and my esx amp (which isn't the easiest to configure either).
This was even after I brought the amps to them with everything but the gains
preconfigured. I had to go to the frikken supermarket parking lot in the
middle of the night to mess with everything because i don't trust the
scumbags who live around me. :P