Well, the level three speakers feature 6.5" woofers. Chances are if you are going to keep your receiver crossed over at 80 or 100 Hz., the level two speakers will suffice. Then again, the tweeters in the level three speakers are also upgraded to ribbon tweeters. There could be a big difference in sound.
Since you are looking at a 7.1 setup, why not just go with a 5.1 setup for now. You could opt for the level threes from the start and add the additional two speakers when you have another $300.
