Hmm good point. I opened some of the tools I ennjoy a lot and it seems they run 12 db/oct in slope. Witch makes 3 band a valid offer for smooth level controlle BUT it will not keep the narrow area 2-4 KHz in control.
Really it is more like 2,45 KHz to 2,85 KHz depending on where the brand of driver has its distortion.
Maybe my fellow Danes got it right when they choose to handle this as two not directly related issues. If this is the problem of the day it goes to the dyn eq and not the mulitiband.
This way you can keep the multiband 3 band with 12 db/oct. The steeper you devide the more you degrade the audio, the more times you devide and summe the more you degrade the audio.
You can always make the slopes ajustable from 12 to 24 and make it 4 band with a bypass option for each band. More programming for you 
