FireQOS: Min/Max guaranteed from ISP

Hello Costa and all other readers!
I've a simple question for FireQOS (this new interesting tool)

In case of "Min/Max bandwidth guaranteed from ISP" how to set the class?

Here an example (simplified):

ISP: MIN 6Mbit / MAX 10Mbit (UP/DOWN)
(I'm not able to know when my ISP allows me more than 5Mbit)

CONFIG:
----------
DEVICE=eth0
INPUT_SPEED=10mbit

interface $DEVICE in input rate $INPUT_SPEED balanced

class a min 2mbit max 10mbit
  match ...
class b min 2mbit max 10mbit
  match ...
class c min 2mbit max 10mbit
  match ...
----------

Is it a right config or I need other "precautions"?
I'm not able to know when and where my packet are slowed and prevent saturation.

Best regars

---
Sim