Pull to the five level?

[ulven]

void

AKT

AJxxx

Axxxx

 

 

So 4♠ is one off against 6♦ making.

 

Is 4NT a serious alternative to X with these suits?

The choice of 4NT or X depends on your partnership agreements. If 'purely' takeout then X fits the bill.

 

My agreement is to pull if believing in making a contract of our own, which our hand has insufficient playing strength to think.

 

In our partnership, we would bid 4NT on the hand above as we can see that partner is very likely pass if we double and that it's more likely to be wrong than right. The chance of finding a fit is good and there's the added possibility that the next hand competes to 5S when wrong.