Okay, barefoot. I'll try to give you a short answer.
Other than for just tweaking the sound quality, can you explain to me a little more how you use the tone controls to "perform"?
The only dj's that would probably use a "minimalistic" mixer would be a
turnbtablist and/or a
newbies.
I've noticed that when I'm in Paris (@ the DMC shop) or London (@Deal Real or Mr. Bongos) the scratch dj's use the tone controls as an "effect" while they are doing "studder" scratches. They bring the low's or hi's in and out as they are doing the "studder" scratch.
I would use the controls for that reason AND
I would use it when I am cutting a phrase from a record (take out the "lows" and turn up the hi's). That would help you to hear the vocals, but cut out the kick, snare, and music of the passage I was cutting.
You would need to have a GAIN control also (for a similar reason).
You have to remember that some of turntablist scratch with the up and down channels.
They also "trick" with one NEW record (on one side) and one OLD record (on the other side).
There are few other reasons, but I might start sounding somewhat redundant.
I know some Dj's do things like cut the bass from one channel and the highs from the other, then mix them.
On one hand, the experienced club dj would use this technique to control the crowd and to perfectly blend the two records, while controling the start time in which the crowd hears the new record blending in with the record you are mixing out.
Again, I say, an experienced club dj would not be spinning with a mixer that does not have EQ's on all channels and that doesn't have GAIN's on all channels either. (Not to say that the exp. dj couldn't use a "bare bones" mixer, they probably wouldn't unless they had to use a "bare bones" mixer. But, then I'm sure that a specific "mixer" would be named and included in their contract rider).
On the other hand, an inexperienced dj would take all the bass out of
BOTH records when blending, to mask the fact that their blend is not "tight" (perfectly on beat or melody). In other words "cheating" (but... sometimes you gotta do what you gotta do...).
Oh yeah. How is the Hampster switch used? Do a lot of DJ's use it?
Yes, a lot of the scratch dj's use this feature. In essence, this is what it does... It reverses the crossfader. Instead of TT1 being on the LEFT and TT2 being on the RIGHT, you flip the switch or knob, and VOILA,
the TT1 is on the RIGHT and TT2 is on the LEFT.
It is used for scatching. The sound of the scratch changes because of the way you click the fader (crossfader).
Say for instance, you are not ambidextrous. And you are "cutting" with your LEFT (left hand on record, right hand on the fader). Now the normal way to do a complex scratch (flare or crab) would be to use your thumb as the "spring" (to click/push the fader to the right,
away), while you use 2 to 4 of your fingers to tap the fader toward the center.
Now, with the HAMSTER switch engaged you would use your thumb (as the "spring") to push the fader away from the left side
toward the middle, while you use 2 to 4 of your fingers to click/push the fader back toward the LEFT side.

(hope you understood that, if not I'll look for a link to a turntablist site, so you can hear what I am saying).
Alright, sorry about the long post. I tried not to make it too long.
peace...
spin