Re: Need help picking either 6x9 or 6 1/2 rear speakers.
Instead of spending the money on front speakers, back speakers, and enclosures... I highly recommend getting a set of component speakers for the front that can handle a decent amount of power. Loud comps up front > coax's all around. I've had the exact same highs setup that you are preparing to go with.... and I now have what I am suggesting. Believe me when I say it is a HUGE step up in volume, clarity, and imaging.
HU: Pioneer DEH-80PRS
Front stage: PHD FB 6.1PRO & Vifa XT25BG60-04
Sub stage: '05 RE XXX 12" w/Fi recone
Highs Amp: Kenwood Excelon XR-4S
Lows Amp: MMATS D300HC
The Rest: AT 60 mil, Optima Redtop underhood and Yellowtop in trunk, Big 3 and front to rear +/- runs in Monster Cable 1/0