Okay, for beginners, none of your links go to any actual product. It says "404 - page not found!".
So I can't help you out with the actual products now, but I can tall you this. On your "side question": to get 6" speakers without tweeters in them you need to either search the entire earth or buy a component set with has a seperate tweeter and a midrange speaker. You're right, it is redundant to have two sets a tweeters. And, if they are both not aimed directly in the same way, the same sound will hit you ears at two different times. It will be almost unnoticable, but you sound like a car audio guy, so you might hear it. In conclusion, update your links so that I can look at these speakers and remember that anything is better than that piece of a "sound system" that is the Mach 460. That is all, talk at you later.