I think you might be surprised if you had a thousand dollar set of speakers to compare yours with. You might like yours better though, who knows?
As far as refoaming the one woofer, I read somewhere that a bicycle inner tube, if cut right, will work great as a surround. and since it's rubber it'll outlast your supertweeters probably. Just make sure you use an environmentally conscious adhesive to put it on. You know, lessen your carbon footprint a little more.