More drivers are not always a waste.
Let's get one thing clear....the Sansui's up to the 2500 series were great(maybe the 3500s too, though I never had any). After that, the woofers went up and up in size, and the cabinets turned to sh** for depth.
On many models, the clarity dials determined only the cripness of say one midrange speaker. The other was always dedicated, and remained constant despite switching of the knobs (Soft, neutral clear) This gave it a 4-way feel, and when listening to say hendrix or Zeppelin, the guitar can come alive. Therefore I must say, Sansui did have a purpose for 2 mids on at least SOME of their moels, and the later crap boxes gave them a bad name.
Listen to Jack Johnson on some sp-200 or sp-2500x, or sp-1700 (smaller mids, not quite the same)
The 2 tweeters help with dispersion, if you set your speakers at listening level like I do. It gives a larger sound field.
But if you place any speaker in a crappy room, it will suck. Period. So That is just my opinion from my couch