I expect the mega peaky means hard to drive, as in all or nothing. I haven't driven a MJTD, but from those taht I have I've picked up that they are not at all like that, but instead are very drivable engines.
I looked on buyacar.co.uk and saw the Stilo is now 1.4 Petrol or the 1.9 Diesel...
If mega peaky means what you say, i have to say mine isn't like that.
It's very drivable. The power doesn't come like a kick in the back, it's just there.