I think that powerful TD engines are great for lots of driving.
For B-roads though, I favour a balanced engine with low-down torque and a linear torque curve all the way to a high red-line. Its not asking the impossible as the Willy F7R certainly does this, but Ive yet to see a TD with these characteristics. You need to be able to use the throttle to control the car while still steering... I think the "sudden" power delivery of a TD is not suitable for this beyond a small rev band.
Since a hot hatch - and a Renault in particular - should be in its element along B-roads, I think current TDs are unsuitable for such a car.
By all means, make and market it as a refined cruiser - but I think it would spoil the illustrious back-road fun lineage of Renault hot hatches.