Ken, I have it. It only can access engine and transmission. I used it on 92 600SEL and here is a live data you can see on LH:
O2 Sensor voltage, mV
S/A CTP (Idle), kg/h
S/A Lower Partial load
S/A Upper Partial Load
Lambda, %
Battery, V
RPM
Basic Injection Duration, mS
Injection duration correction
Hot Wire air mass, kg/h
Hot Wire Voltage
Pressure, mbar
Coolant Temp 1 *C
Coolant Temp 2
After start enrichment
Deceleration Shut off
Air Pump
Camshaft timing
Intake Air temperature
CTP Idle recognition
Throttle angle
WOT recognition
EGR
Fuel Pump
Canister Purge Duty cycle, %
Speed
Cylinder Shut-Off 1 (7)
Cylinder Shut-Off 2 (8)
Cylinder Shut-Off 3 (9)
Cylinder Shut-Off 4 (10)
Cylinder Shut-Off 5 (11)
Cylinder Shut-Off 6 (12)
LN-SFI Ref Resistor
Circuit 50
Safety Fuel Shut-Off
CAN Reception from DI 1(2)
CAN Reception from EA/CC/ISC
CAN Reception from LH 2(1)
CAN Transmission from LH 1(2)

You can reset self adaptations. It can also do some activations - EGR, camshaft, shut off individual injectors, purge valve.
It also can read EZL, but I did not have a chance to use it with EZL yet.
The one I got is MTG2500 - has graphing capabilities. Got it on Ebay, and a MB cartrige from SnapOn.
I have mine only for week or so, and did not use it on my other cars yet.
Let me know if you need more details.
Mike