Ok, as for people telling you that you shouldn't run components in the back, it's just simply bunk and internet bandwagon-jumping. Here's why:
People talk about not using rear fill at all. This is true in competition circles, rear-fill is frowned upon, because it detracts from the front image and staging if not implemented extremely carefully.
However, in today's world of video setups and 5.1 theater in the car, as well as most people who couldn't give 2 shits about SQ competition, all they want is something to 'fill up' their car with music. Hell, most people don't even care about stereo separation, much less imaging and staging! Also people say that you should spend the majority of your money on components up front (since this is where the driver sits, and there will always be a driver in the car, but not always rear passengers). Saving money on rear-fill by using coaxials (or not having rear-fill at all) is one way to allow for a bigger budget for better speakers in the front. Arguing against components in the rear is mainly just an argument for monetary savings and installation issues, not sound issues.
However, this poster already has Type R comps, but I would guess those are in the front, and the Type R coax are in the back, making it a moot point. But if people want to have rear speakers, that's their preference and if they're not competing or trying hard to attain imaging and staging, then rear fill is no issue whatsoever.
Personally, I don't use rear fill, and haven't since removing the stock system. In my wife's stock Taurus, I keep the sound faded about 75% to the front, because my 2-y/o son rides in the back and I don't want it blaring in his ears, although I generally don't turn it up much at all when he's in the car. But I can see the point that for most people, it makes little to no difference, and in fact, most novice or new amateur enthusiasts will pick a rear-fill system as their preference over a front-stage only system. This has been my experience in the past. Do I miss rear-fill? Not a bit.
Now...
That Alpine amp is 70x4 @ 4 ohms, which isn't bad at all for most entry-level components. The one's you've listed will probably do fairly well with that amount of power, but if you've got the opportunity to bi-amp them, I think you'll be pretty pleased with the improvement. And you could run the rear-fill off your deck, instead of the amp (assuming this isn't what you were already planning). In a car that small, you can easily fill it up with a great set of bi-amped components, and those rear coaxes can fade out of the picture. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif I can't comment specifically on those sets, although the mids on the Pioneers have had their praises sung many times on the forums. The tweets are nothing special, and some people say they kinda crap out at moderate-to-high volume levels.
Other than that, I can't help ya. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
Good luck!