While I'm sure Rockford uses much better materials in their construction than the typical OEM speakers, I'd be a little concerned they are matched in power. You can hurt a new speaker by underpowering it.
I guess we need a guinea pig...
Careful as to relating to blowing or hurting a subwoofer by under powering it. You can under power a subwoofer all day long, as long as you are not sending clipped signals (turning bass-boost up, gain, etc).
The RF subwoofers should be fine as a replacement for the OEM woofers. Me personally I would run a separate amplifier (2-channel most likely) since it would just be for the replacement door subwoofers.
On the other hand my project for the summer is to rip everything stock (shaker500) out and put my box in the back 2-12's and replace all factory speakers with some nice component sets and a deck to match it all