Frederic,
I bought a JCUT 6090A a couple of years ago. I have been very happy with it.
My machine is smaller than the one you are considering but it is rock solid. The machine you are looking at has rack and pinion drives for X and Y where mine has ballscrew for X and Y. I think that is a better system, especially for a larger machine. I think it might allow you to move quicker from one point to another. Z is ballscrew on your machine as well as mine. Since it is only moving a short distance that is fine. It also is a better control for the vertical axis than rack since it will keep Z from dropping when power is removed.
My spindle is only 2.2kw (3hp) and I believe the spindle on the machine you are looking at is 3kw (4hp). I only cut wood and plastic with mine, but it works very well. I believe the 4hp should be all you need for MDF.
The vacuum table is probably a great option. I didn't get one and sometimes I wish I had.
I dealt with Mandy. She was very helpful to me and I would gladly deal with her again.
From Wikipedia - "..butter knife..any table knife designed with a dull edge and rounded point". I've never claimed to be the sharpest knife in the drawer!