Chessrock,
I don't know that if you said, "Yea, I got me a vintage MP7...", that you will get any one in.
Hiphop seems to like to move forward rather quickly and not linger on "vintage" tools like I personaly would (pre-CBS Fenders, old Martins, etc....)
But an MP7 would definatly help you a bit. It is MIDI so you can also use a keyboard control for a wider range of effects at once.
Granted with a beatbox like the MP7, your client will have to sit down and program beats. That takes a while.............

...good for you, turn off for them when they realize the studio timeclock is ticking.
But at the same time you can come up with beats on the spot and live with it too.
Ooohhhhhhs and Aaahhhhhhs??? After they hear the quality it dishes out.
But the Akai samplers are some serious tools for a studio. They work in conjunction with the beatboxes and all those damn CDs that say DRUM LOOPS.
You can even mic stuff and send it to the Sampler. Then when ever you push one of those 16 pads, it plays something. And if you push it again, it stop and starts again.
But
the EMU MP7 is going for about $500-$550 USED for one in mint conditioned. Its up to you if its worth it. (But if all the stuff coming in is garbage and they leave with quality......word spreads like wildfire.
...and hiphop is a BILLION dollar industry.)