Its not the door panels that need to be sealed, its any open holes on the door skin tiself that should be sealed for optimum lowend output. I would lean towards the dyns since theyre one of a few component sets that actually sound good with a passive crossover. They are power hungry and Id expect to feed them at least 250 a side.
There are a ton of options for amplification and its not neccesary to sepnd a rediculous amount of money, The differences are inaudible to the human ear and some high end amplifiers "color" the sound and take away from what the Dyns can accomplish. Check out Audisons SRX line or Jl slash or HD. Memphis also makes some sleek powerful amps that can be had very reasonably priced wit ha 2 yr warranty from your local dealer.