The question Mica pointed out is while Mids around 200Hz adds body or thickness, but when they get around 400Hz it tends to muffles your tone. Then, above 600Hz, it may thin your sound or enhance articulation. While 1.5KHz is usualy good to open your tone in finger style, it may be not that good for Slapping. Slapper tends to cut mids around 800Hz~1KHz, but some boosts at 2.5KHz or even higher.
So, there is no such thing as Mids. There are Mids and Mids, thats why the Low Pass Filter and Switch can be so helpfull and versatile (not to mention the continuous variable filter).
You have to be very shure about wich frequency (and bandwidth) you need to control to ask for designing such circuit.