If you turn off the tweeters up high you may gain some imagine but you probably loose staging. The music will probably be more focused but everything will seem lower. Its a trade off you make. It would probably be hard to get good stage height without at least kickpannels.

As for the power its always better to have more headroom imo. It seems to really help with dynamics. As long as you don't keep it cranked and blow the speakers. Are you afraid of the wire melting or something? Is that why you dont want to run the amp to the front speakers?